NUVEEN FLOATING RATE INCOME FUND (0001276533) (Filer)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM N-CSR

CERTIFIED SHAREHOLDER REPORT OF REGISTERED

MANAGEMENT INVESTMENT COMPANIES

Nuveen Floating Rate Income Fund

(Exact name of registrant as specified in charter)

Nuveen Investments

333 West Wacker Drive

Chicago, Illinois 60606

(Address of principal executive offices) (Zip code)

Mark L. Winget

Vice President and Secretary

333 West Wacker Drive

Chicago, Illinois 60606

(Name and address of agent for service)

Registrant’s telephone number, including area code:

(800) 257-8787

Date of fiscal year end:

July 31

Date of reporting period:

July 31, 2026

Nuveen

Closed-End

Funds

Annual

Report

Table

of Contents

Important Notices

JPC - Fund merger:

Effective prior to market open on September 22, 2025, Nuveen Preferred Securities & Income Opportunities Fund (JPI) was merged into JPC. Refer to the Notes to Financial Statements within this report for further details on the merger.

JPC and NPFD - Recent market factors:

JPC and NPFD have substantial allocations to preferred and contingent capital securities issued by U.S. and non-U.S. banks and other financial institutions. Given the increases in prevailing interest rates and other market factors, these securities continue to be subject to heightened volatility and may, ultimately, detract from Fund performance.

Discussion of Fund Performance

Nuveen Floating Rate Income Fund (JFR)

Nuveen Credit Strategies Income Fund (JQC)

Nuveen Preferred & Income Opportunities Fund (JPC)

Nuveen Variable Rate Preferred & Income Fund (NPFD)

These Funds feature portfolio management by Nuveen Asset Management, LLC (NAM), an affiliate of Nuveen Fund Advisors, LLC, the Funds’ investment adviser. The portfolio managers for JFR are Scott Caraher and Coale Mechlin. The portfolio managers for JQC are Scott Caraher, Himani Trivedi, James Kim and Coale Mechlin. The portfolio managers for JPC and NPFD are Douglas Baker, CFA, and Brenda Langenfeld, CFA.

Below is a discussion of Fund performance and the factors that contributed and detracted during the 12-month reporting period ended July 31, 2026. For more information on Fund investment objectives and policies, please refer to the Shareholder Update section at the end of the report.

Nuveen Floating Rate Income Fund (JFR)

What factors affected markets during the reporting period?

What key strategies were used to manage the Fund during the reporting period?

How did the Fund perform and what factors affected relative performance?

For the 12-month reporting period ended July 31, 2026, JFR returned 5.82%. The Fund outperformed the S&P UBS Leveraged Loan Index, which returned 4.27%.

Top contributors to relative performance

Top detractors from relative performance

Nuveen Credit Strategies Income Fund (JQC)

What factors affected markets during the reporting period?

What key strategies were used to manage the Fund during the reporting period?

How did the Fund perform and what factors affected relative performance?

For the twelve-month reporting period ended July 31, 2026, JQC returned 5.67%. The Fund outperformed the JQC Blended Benchmark, which returned 4.46%.

Top contributors to relative performance

Top detractors from relative performance

Nuveen Preferred & Income Opportunities Fund (JPC)

What factors affected markets during the reporting period?

Discussion of Fund Performance

(continued)

What key strategies were used to manage the Fund during the reporting period?

How did the Fund perform and what factors affected relative performance?

For the twelve-month reporting period ended July 31, 2026, JPC returned 6.30%. The Fund outperformed the JPC Blended Benchmark, which returned 5.06%.

Top contributors to relative performance

Top detractors from relative performance

6

Nuveen Variable Rate Preferred & Income Fund (NPFD)

What factors affected markets during the reporting period?

What key strategies were used to manage the Fund during the reporting period?

How did the Fund perform and what factors affected relative performance?

For the twelve-month reporting period ended July 31, 2026, NPFD returned 6.37%. The Fund outperformed the NPFD Blended Benchmark, which returned 5.83%.

Top contributors to relative performance

Top detractors from relative performance

Discussion of Fund Performance

(continued)

This material is not intended to be a recommendation or investment advice, does not constitute a solicitation to buy, sell or hold a security or an investment strategy, and is not provided in a fiduciary capacity. The information provided does not take into account the specific objectives or circumstances of any particular investor, or suggest any specific course of action. Investment decisions should be made based on an investor’s objectives and circumstances and in consultation with his or her advisors.

Certain statements in this report are forward-looking statements. Discussions of specific investments are for illustration only and are not intended as recommendations of individual investments. The forward-looking statements and other views expressed herein are those of the portfolio managers as of the date of this report. Actual future results or occurrences may differ significantly from those anticipated in any forward-looking statements, and the views expressed herein are subject to change at any time, due to numerous market and other factors. The Funds disclaim any obligation to update publicly or revise any forward-looking statements or views expressed herein.

For financial reporting purposes, the ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s Group (S&P), Moody’s Investors Service, Inc. (Moody’s) or Fitch, Inc. (Fitch). This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings, while BB, B, CCC, CC, C and D are below investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

Bond insurance guarantees only the payment of principal and interest on the bond when due, and not the value of the bonds themselves, which will fluctuate with the bond market and the financial success of the issuer and the insurer. Insurance relates specifically to the bonds in the portfolio and not to the share prices of a Fund. No representation is made as to the insurers’ ability to meet their commitments.

Refer to the Glossary of Terms Used in this Report for further definition of the terms used within this section.

8

Common Share Information

COMMON SHARE DISTRIBUTION INFORMATION

The following information regarding each Fund’s distributions is current as of July 31, 2026.

Each Fund’s distribution policy, which may be changed by the Board, is to make regular monthly cash distributions to holders of its common shares (stated in terms of a fixed cents per common share dividend distribution rate which may be set from time to time). Each Fund intends to distribute all or substantially all of its net investment income each year through its regular monthly distribution and to distribute realized capital gains at least annually. In addition, in any monthly period, to maintain its declared per common share distribution amount, a Fund may distribute more or less than its net investment income during the period. In the event a Fund distributes more than its net investment income during any yearly period, such distributions may also include realized gains and/or a return of capital. To the extent that a distribution includes a return of capital the NAV per share may erode. The practice of maintaining a stable distribution level had no material effect on each Fund’s investment strategy during the most recent fiscal period and is not expected to have such an effect in future periods, however, distributions in excess of Fund returns will cause its NAV per share to erode. For additional information, refer to the distribution information section below and in the Notes to Financial Statements herein.

The following table provides the sources of distributions and may include amounts attributed to realized gains and/or returns of capital. A return of capital may occur, for example, when some or all of the money that you invested in a Fund is paid back to you. A return of capital distribution does not necessarily reflect a Fund’s investment performance and should not be confused with “yield” or “income.” The Funds attribute these estimates equally to each regular distribution throughout the year.

The amounts and sources of distributions reported in this notice are for financial reporting purposes and are not being provided for tax reporting purposes. The actual amounts and character of the distributions for tax reporting purposes will be reported to shareholders on Form 1099-DIV, which will be sent to shareholders shortly after calendar year-end. Because distribution source estimates are updated throughout the current fiscal year based on a Fund’s performance, those estimates may differ from both the tax information reported to you in your Fund’s 1099 statement, as well as the ultimate economic sources of distributions over the life of your investment. The figures in the table below provide the sources of distributions and may include amounts attributed to realized gains and/or returns of capital. More details about each Fund’s distributions are available on www.nuveen.com/en-us/ closed-end-funds.

Data as of July 31, 2026

NUVEEN CLOSED-END FUND DISTRIBUTION AMOUNTS

The Nuveen Closed-End Funds’ monthly and quarterly periodic distributions to shareholders are posted on www.nuveen.com and can be found on Nuveen’s enhanced closed-end fund resource page, which is at https://www.nuveen.com/resource-center-closed-end-funds, along with other Nuveen closed-end fund product updates. To ensure timely access to the latest information, shareholders may use a subscribe function, which can be activated at this web page (https://www.nuveen.com/subscriptions).

COMMON SHARE EQUITY SHELF PROGRAMS

During the current reporting period, the following Fund was authorized by the Securities and Exchange Commission to issue additional common shares through an equity shelf program (Shelf Offering). Under these programs, the Fund subject to market conditions, may raise additional capital from time to time in varying amounts and offering methods at a net price at or above the Fund’s NAV per common share. The maximum aggregate offering under these Shelf Offerings, are as shown in the accompanying table.

Common Share Information

(continued)

During the current reporting period, the following Fund sold common shares through its Shelf Offering at a weighted average premium to its NAV per common share in the accompanying table.

Refer to Notes to Financial Statements for further details of Shelf Offerings and the Fund’s transactions.

COMMON SHARE REPURCHASES

The Funds’ Board of Trustees reauthorized an open-market share repurchase program, allowing each Fund to repurchase and retire an aggregate of up to approximately 10% of its outstanding common shares.

Refer to the Notes to Financial Statements for further details on share repurchases and Fund’s transactions.

10

About the Funds’ Benchmarks

ICE BofA U.S. All Capital Securities Index:

An index designed to measure the performance of investment grade and below investment grade fixed rate and fixed-to-floating rate, USD-denominated hybrid corporate and preferred securities publicly issued in the U.S. domestic market. Index returns assume reinvestment of distributions, but do not reflect any applicable sales charges or management fees.

ICE BofA U.S. High Yield Index:

An index designed to measure the performance of USD-denominated below investment grade corporate debt publicly issued in the U.S. domestic market. Index returns assume reinvestment of distributions, but do not reflect any applicable sales charges or management fees.

ICE USD Contingent Capital Index:

An index designed to measure the performance of USD-denominated contingent capital debt publicly issued in the major domestic and Eurobond markets, including investment grade and below investment grade issues. Index returns assume reinvestment of distributions, but do not reflect any applicable sales charges or management fees.

ICE Variable Rate Preferred & Hybrid Securities Index:

An index designed to measure the performance of floating-and variable-rate investment grade and below investment grade USD-denominated preferred stock and hybrid debt publicly issued by corporations in the U.S. domestic market. Index returns assume reinvestment of distributions, but do not reflect any applicable sales charges or management fees.

S&P UBS Leveraged Loan Index:

An index designed to measure the performance of the USD-denominated leveraged loan market. The index includes issuers from developed countries; issuers from developing countries are excluded. Index returns assume reinvestment of distributions, but do not reflect any applicable sales charges or management fees.

Fund Performance, Leverage and Holdings Summaries

The Fund Performance, Leverage and Holding Summaries for each Fund are shown below within this section of the report.

Fund Performance

Performance data for each Fund shown below represents past performance and does not predict or guarantee future results.

Current performance may be higher or lower than the data shown. Returns do not reflect the deduction of taxes that shareholders may have to pay on Fund distributions or upon the sale of Fund shares. Returns at NAV are net of Fund expenses, and assume reinvestment of distributions. Comparative index return information is provided for the Fund’s shares at NAV only. Indexes are not available for direct investment.

Total returns for a period of less than one year are not annualized (i.e. cumulative returns). Since inception returns are shown for share classes that have less than 10-years of performance. For performance, current to the most recent month-end visit Nuveen.com or call (800) 257-8787.

Impact of Leverage

One important factor impacting the returns of the Funds’ common shares relative to their comparative benchmarks was the Funds’ use of leverage through bank borrowings, Taxable Fund Preferred Shares (TFP) and/or reverse repurchase agreements. The Funds use leverage because our research has shown that, over time, leveraging provides opportunities for additional income. The opportunity arises when short-term rates that a Fund pays on its leveraging instruments are lower than the interest the Fund earns on its portfolio securities that it has bought with the proceeds of that leverage.

However, use of leverage can expose Fund common shares to additional price volatility. When a Fund uses leverage, the Fund’s common shares will experience a greater increase in their net asset value if the securities acquired through the use of leverage increase in value, but will also experience a correspondingly larger decline in their net asset value if the securities acquired through leverage decline in value. All this will make the shares’ total return performance more variable over time.

In addition, common share income in levered funds will typically decrease in comparison to unlevered funds when short-term interest rates increase and increase when short-term interest rates decrease. In recent quarters, fund leverage expenses have generally tracked the overall movement of short-term interest rates. While fund leverage expenses are higher than their prior year lows, leverage nevertheless continues to provide the opportunity for incremental common share income, particularly over longer-term periods.

Leverage Ratios

Each Fund’s Effective Leverage and Regulatory Leverage Ratios are set forth below. “Effective Leverage” is a Fund’s effective economic leverage, and includes both regulatory leverage and the leverage effects of certain derivative and other investments in a Fund’s portfolio that increase the Fund’s investment exposure. “Regulatory Leverage” consists of preferred shares or borrowings of a Fund. Regulatory Leverage is a part of a Fund’s capital structure. Regulatory leverage is subject to asset coverage limits set forth in the Investment Company Act of 1940. A Fund, however, may from time to time borrow for temporary purposes, typically on a transient basis in connection with its day-to-day operations, primarily in connection with the need to settle portfolio trades. Such temporary borrowings are excluded from the calculation of a Fund’s Effective Leverage and Regulatory Leverage ratios.

Holding Summaries

The Holdings Summaries data relates to the securities held in each Fund’s portfolio of investments as of the end of this reporting period. It should not be construed as a measure of performance for the Fund itself. Holdings are subject to change. Refer to the Fund’s Portfolio of Investments for individual security information.

For financial reporting purposes, the ratings disclosed are the highest rating given by one of the following national rating agencies: Standard & Poor’s, Moody’s Investors Service, Inc. or Fitch, Inc. This treatment of split-rated securities may differ from that used for other purposes, such as for Fund investment policies. Credit ratings are subject to change. AAA, AA, A and BBB are investment grade ratings; BB, B, CCC, CC, C and D are below investment grade ratings. Holdings designated N/R are not rated by these national rating agencies.

*For purposes of Fund performance, relative results are measured against the S&P UBS Leveraged Loan Index.

Daily Common Share NAV and Share Price

Growth of an Assumed $10,000 Investment as of July 31, 2026 - Common Share Price

Performance Overview and Holdings Summaries as of July 31, 2026

(continued)

Leverage and Holdings

*For purposes of Fund performance, relative results are measured against the JQC Blended Benchmark. As of August 7, 2023, the Fund’s Blended Benchmark consists of: 1) 75% S&P UBS Leveraged Loan Index and 2) 25% ICE BofA U.S. High Yield Index. Prior to August 7, 2023, relative results were measured against the S&P UBS Leveraged Loan Index.

Daily Common Share NAV and Share Price

Growth of an Assumed $10,000 Investment as of July 31, 2026 - Common Share Price

Performance Overview and Holdings Summaries as of July 31, 2026

(continued)

Leverage and Holdings

*For purposes of Fund performance, relative results are measured against the JPC Blended Benchmark. The Fund’s Blended Benchmark consists of:

1) 60% ICE BofA U.S. All Capital Securities Index and 2) 40% ICE USD Contingent Capital Index.

Daily Common Share NAV and Share Price

Growth of an Assumed $10,000 Investment as of July 31, 2026 -

Common Share Price

Performance Overview and Holdings Summaries as of July 31, 2026

(continued)

Leverage and Holdings

*For purposes of Fund performance, relative results are measured against the NPFD Blended Benchmark. The Fund’s Blended Benchmark consists of

1) 80% ICE Variable Rate Preferred & Hybrid Securities Index and 2) 20% ICE USD Contingent Capital Index.

Daily Common Share NAV and Share Price

Growth of an Assumed $10,000 Investment as of July 31, 2026 -

Common Share Price

Performance Overview and Holdings Summaries as of July 31, 2026

(continued)

Leverage and Holdings

Report of Independent Registered Public Accounting Firm

To the Board of Trustees and Shareholders of Nuveen Floating Rate Income Fund, Nuveen Credit Strategies Income Fund, Nuveen Preferred & Income Opportunities Fund and Nuveen Variable Rate Preferred & Income Fund

Opinions on the Financial Statements

We have audited the accompanying statements of assets and liabilities, including the portfolios of investments, of Nuveen Floating Rate Income Fund, Nuveen Credit Strategies Income Fund, Nuveen Preferred & Income Opportunities Fund and Nuveen Variable Rate Preferred & Income Fund (hereafter collectively referred to as the “Funds”) as of July 31, 2026, the related statements of operations and cash flows for the year ended July 31, 2026, the statements of changes in net assets for each of the two years in the period ended July 31, 2026, including the related notes, and the financial highlights for each of the two years in the period ended July 31, 2026 (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of each of the Funds as of July 31, 2026, the results of each of their operations and each of their cash flows for the year then ended, the changes in each of their net assets for each of the two years in the period ended July 31, 2026 and each of the financial highlights for each of the two years in the period ended July 31, 2026 in conformity with accounting principles generally accepted in the United States of America.

The financial statements of the Funds as of and for the year ended July 31, 2024 and the financial highlights for each of the periods ended on or prior to July 31, 2024 (not presented herein, other than the financial highlights) were audited by other auditors whose report dated September 27, 2024 expressed an unqualified opinion on those financial statements and financial highlights.

Basis for Opinions

These financial statements are the responsibility of the Funds’ management. Our responsibility is to express an opinion on the Funds’ financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Funds in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits of these financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. Our procedures included confirmation of securities owned as of July 31, 2026 by correspondence with the custodian, transfer agents, agent banks and brokers; when replies were not received from transfer agents, agent banks or brokers, we performed other auditing procedures. We believe that our audits provide a reasonable basis for our opinions.

/s/ PricewaterhouseCoopers LLP

Chicago, Illinois

September 25, 2026

We have served as the auditor of one or more investment companies in Nuveen Funds since 2002.

Portfolio of Investments July 31, 2026

JFR

Portfolio of Investments July 31, 2026

(continued)

JFR