Company: IMRX
Filing Date: 2025-09-08
Form Type: 424B3
Source: 0001104659-25-088317
Chunk: 1

Company: Immuneering Corp
Filing Date: 2025-09-08
Form: 424B3
Chunk 1
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SIDER BEFORE INVESTING IN OUR SECURITIES.

Our Class A common stock is listed on the Nasdaq Global Market under the symbol “IMRX.” On August 29, 2025, the last reported sale price of our Class A common stock on the Nasdaq Global Market was $5.75 per share.

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

<div align='center'>The date of this prospectus is September 8, 2025.</div>

TABLE OF CONTENTS

TABLE OF CONTENTS

| ​ | ABOUT THIS PROSPECTUS                                           | ​ | ​ | ​ | ​ |  1 | ​ | ​ |
| ​ | SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS               | ​ | ​ | ​ | ​ |  2 | ​ | ​ |
| ​ | WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE | ​ | ​ | ​ | ​ |  3 | ​ | ​ |
| ​ | THE COMPANY                                                     | ​ | ​ | ​ | ​ |  5 | ​ | ​ |
| ​ | RISK FACTORS                                                    | ​ | ​ | ​ | ​ |  6 | ​ | ​ |
| ​ | USE OF PROCEEDS                                                 | ​ | ​ | ​ | ​ |  7 | ​ | ​ |
| ​ | DESCRIPTION OF SECURITIES                                       | ​ | ​ | ​ | ​ |  8 | ​ | ​ |
| ​ | PRIVATE PLACEMENT OF SECURITIES                                 | ​ | ​ | ​ | ​ | 16 | ​ | ​ |
| ​ | SELLING STOCKHOLDERS                                            | ​ | ​ | ​ | ​ | 18 | ​ | ​ |
| ​ | PLAN OF DISTRIBUTION                                            | ​ | ​ | ​ | ​ | 21 | ​ | ​ |
| ​ | LEGAL MATTERS                                                   | ​ | ​ | ​ | ​ | 23 | ​ | ​ |
| ​ | EXPERTS                                                         | ​ | ​ | ​ | ​ | 23 | ​ | ​ |

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TABLE OF CONTENTS

### ABOUT THIS PROSPECTUS
This prospectus is part of a registration statement that we filed with the U.S. Securities and Exchange Commission, or the SEC, using a “shelf” registration process. By using a shelf registration