Filed Pursuant to Rule 424(b)(3)

Registration No. 333-266810

PROSPECTUS SUPPLEMENT NO. 8

(To Prospectus dated August 25, 2022)

UP TO 500,000 SHARES OF COMMON STOCK

This prospectus supplement supplements the prospectus, dated August 25, 2022 (the “Prospectus”), which forms a part of our registration statement on Form S-1 (No. 333-266810). This prospectus supplement is being filed to update and supplement the information in the Prospectus with the information contained in our Current Report on Form 8-K filed with the Securities and Exchange Commission on January 27, 2023 (the “Current Report”). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to the offer and sale from time to time by Ampere Computing LLC or its permitted transferees (“Ampere” or the “selling stockholder”) of up to 500,000 shares (the “Shares”) of common stock, par value $0.0001 (the “common stock”), of the Company, issued upon the exercise of the vested portion of that certain warrant issued to the selling stockholder (the “Ampere Warrant”) pursuant to the warrant subscription agreement, dated as of October 6, 2021, by and between Legacy Rigetti (as defined below) and Ampere (the “Warrant Subscription Agreement”), for an aggregate purchase price (including amounts for exercise) of $10,000,000, or $10.00 per share. The Shares consist of 500,000 outstanding shares of common stock issued in connection with the exercise of the vested portion of the Ampere Warrant and receipt by the Company of an aggregate $5,000,000 (including aggregate exercise price).

The selling stockholder may offer, sell or distribute all or a portion of the Shares publicly or through private transactions at prevailing market prices or at negotiated prices. We will not receive any of the proceeds from such sales of the Shares.

We will bear all costs, expenses and fees in connection with the registration of these Shares, including with regard to compliance with state securities or “blue sky” laws. The selling stockholder will bear all commissions and discounts, if any, attributable to their sale of Shares. See the section entitled “Plan of Distribution.”

This prospectus supplement updates and supplements the information in the Prospectus and is not complete without, and may not be delivered or utilized except in combination with, the Prospectus, including any amendments or supplements thereto. This prospectus supplement is qualified by reference to the Prospectus, including any amendments or supplements thereto, except to the extent that the information in this prospectus supplement updates and supersedes the information contained therein.

The common stock is listed on The Nasdaq Capital Market (“Nasdaq”) under the symbol “RGTI.” On January 26, 2023, the last reported sales price of the common stock as reported on Nasdaq was $0.808 per share.

We are an “emerging growth company” as defined under U.S. federal securities laws and, as such, have elected to comply with reduced public company reporting requirements. The Prospectus complies with the requirements that apply to an issuer that is an emerging growth company.

Investing in our securities involves a high degree of risks. You should review carefully the risks and uncertainties described in the section titled “Risk Factors“ beginning on page 16 of the Prospectus, and under similar headings in any amendments or supplements to the Prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities, or passed upon the accuracy or adequacy of the prospectus or this prospectus supplement. Any representation to the contrary is a criminal offense.

Prospectus Supplement dated January 27, 2023.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): January 25, 2023

RIGETTI COMPUTING, INC.

(Exact name of registrant as specified in its charter)

(510) 210-5550

(Registrant’s telephone number, including area code)

N/A

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligations of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

On January 25, 2023, Rigetti Computing, Inc. (the “Company”) received a letter from the Listing Qualifications Department of The Nasdaq Stock Market, LLC, (“Nasdaq”), indicating that, based on the closing bid price for the previous 30 consecutive business days, the listing of the Company’s common stock was not in compliance with Nasdaq Listing Rule 5550(a)(2) to maintain a minimum bid price of $1.00 per share (the “Bid Price Rule”).

Nasdaq Listing Rule 5810(c)(3)(A) provides a compliance period of 180 calendar days, or until July 24, 2023 (the “Compliance Date”), to regain compliance. If at any time during this 180-day period the closing bid price of the Company’s common stock is at least $1.00 for a minimum of ten consecutive business days, the Company will regain compliance. If the Company is unable to regain compliance before the Compliance Date, the Company may be eligible for an additional 180 calendar days to satisfy the Bid Price Rule. To qualify, the Company will be required to meet the continued listing requirement for market value of publicly held shares and all other initial listing standards for the Nasdaq Capital Market with the exception of the Bid Price Rule, and will need to provide written notice of its intention to cure the deficiency during such additional compliance period, by effecting a reverse stock split, if necessary. However, if it appears to Nasdaq staff that the Company will not be able to cure the deficiency, or if the Company is otherwise not eligible for the additional compliance period, and the Company does not regain compliance by the Compliance Date, the Nasdaq Capital Market will provide written notification to the Company that its common stock is subject to delisting. At that time, the Company may appeal the delisting determination to a hearings panel pursuant to the procedures set forth in the applicable Nasdaq Listing Rules. However, there can be no assurance that, if the Company does appeal the delisting determination by Nasdaq to the panel, such appeal would be successful.

The Company intends to actively monitor the closing bid price of its common stock and, as appropriate, will consider available options to regain compliance with the Bid Price Rule, including potentially seeking to effect a reverse stock split. There can be no assurance that the Company will be able to regain compliance with Nasdaq’s Listing Rule 5550(a)(2) or will otherwise be in compliance with other Nasdaq listing criteria and that the Company will be able to maintain its listing with Nasdaq.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

Dated: January 27, 2023