Supplemental Prospectus - Form 424B3

Filed Pursuant to Rule 424(b)(3)

Registration No. 333-257731

PROSPECTUS SUPPLEMENT NO. 12

(to Prospectus dated August 6, 2021)

JANUS INTERNATIONAL GROUP, INC.

Up to 114,045,400 Shares of Common Stock

Up to 10,150,000 Warrants

Up to 10,150,000 Shares of Common Stock Underlying Warrants

This prospectus supplement supplements the prospectus dated August 6, 2021 (the "Prospectus"), which forms a part of our registration statement on Form S-1 (No. 333-257731). 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 (the "Commission") on August 16, 2022 (the "Current Report"). Accordingly, we have attached the Current Report to this prospectus supplement.

The Prospectus and this prospectus supplement relate to resale from time to time of up to 114,045,400 shares of our common stock, par value $0.0001 per share (the "Common Stock"), 10,150,000 warrants to purchase Common Stock of the Company (the "Warrants") and 10,150,000 shares of Common Stock issuable upon exercise of the Warrants by the selling securityholders named in the Prospectus (each a "Selling Securityholder" and collectively, the "Selling Securityholders"). The Common Stock may be offered from time to time up to specified limits by one or more of the Selling Securityholders identified in the Prospectus or in any supplement to the Prospectus. See the sections of the Prospectus entitled "Selling Securityholders" and "Plan of Distribution."

Our Common Stock is listed on the New York Stock Exchange ("NYSE") under the symbol "JBI." On August 12, 2022, the closing sale price of our Common Stock was $11.17. Our Warrants were listed on NYSE under the symbol "JBI WS" until November 11, 2021. On November 11, 2021, the closing sale price of our Warrants was $3.80. As of 5:00 p.m., Eastern Time, on November 12, 2021, all of our outstanding Warrants have been redeemed.

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 should be read in conjunction with the Prospectus and if there is any inconsistency between the information in the Prospectus and this prospectus supplement, you should rely on the information in this prospectus supplement.

Investing in our securities involves risk. You should carefully consider the risks that are described in the section captioned "Risk Factors" beginning on page 7 of the Prospectus and under similar headings in any further amendments or supplements to the Prospectus, and in Section 1A. Risk Factors of our Annual Report and our Quarterly Reports on Form 10-Q.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is August 16, 2022

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

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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): August 16, 2022

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Janus International Group, Inc.

(Exact Name of Registrant as Specified in Charter)

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Delaware	001-40456	86-1476200
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification Number)
135 Janus International Blvd., Temple, GA 30179 (Address of Principal Executive Offices, Zip Code)
Registrant's telephone number, including area code: (866) 562-2580

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

☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e 4(c))

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

Title of Each Class	Trading Symbol(s)	Name of Each Exchange on Which Registered
Common Stock, par value $0.0001 per share	JBI	New York Stock Exchange

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. ☐

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Item 2.02. Results of Operations and Financial Condition.

On August 16, 2022, Janus International Group, Inc. (the "Company") issued a press release announcing financial results for the quarter ended July 2, 2022 (the "Earnings Release"). The full text of the Earnings Release is furnished as Exhibit 99.1 to this Current Report on Form 8-K and is available on the investor relations section of the Company's website at https://ir.janusintl.com.

The information in this Item 2.02, including Exhibit 99.1, shall not be deemed "filed" for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), or otherwise subject to the liabilities of that section, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act of 1933, as amended (the "Securities Act"), or the Exchange Act, regardless of the general incorporation language contained in such filing. Without limiting the generality of the foregoing, the text of the press release set forth under the heading entitled "Forward-looking Statements" is incorporated by reference into this Item 2.02.

Item 7.01. Regulation FD Disclosure.

On August 16, 2022, the Company provided an investor presentation that will be made available on the investor relations section of the Company's website at https://ir.janusintl.com. The investor presentation is furnished as Exhibit 99.2 to this Current Report on Form 8-K.

The information in this Item 7.01, including Exhibit 99.2, shall not be deemed "filed" for purposes of Section 18 of the Exchange Act, or otherwise subject to the liabilities of that section, and shall not be incorporated by reference into any registration statement or other document filed under the Securities Act or the Exchange Act, regardless of the general incorporation language contained in such filing. Without limiting the generality of the foregoing, the text of the press release set forth under the heading entitled "Forward-looking Statements" is incorporated by reference into this Item 7.01.

Item 9.01. Financial Statement and Exhibits.

Exhibit Number	Description
99.1	Press Release, dated August 16, 2022
99.2	Investor Presentation, dated August 16, 2022
104	Cover Page Interactive Data File (formatted as inline XBRL).

SIGNATURE

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

Dated: August 16, 2022

JANUS INTERNATIONAL GROUP, INC.

By: /s/ Anselm Wong

Name: Anselm Wong

Title: Chief Financial Officer