Company: RPID
Filing Date: 2025-02-28
Form Type: S-8
Source: 0001380106-25-000061
Chunk: 0

Company: RAPID MICRO BIOSYSTEMS, INC.
Filing Date: 2025-02-28
Form: S-8
Chunk 0
---
<div align='center'>As filed with the Securities and Exchange Commission on February 28, 2025</div>

#### Registration No. 333-

### UNITED STATES

### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### FORM S-8

### REGISTRATION STATEMENT

#### Under the Securities Act of 1933

#### Rapid Micro Biosystems, Inc.
<div align='center'>(Exact name of registrant as specified in its charter)</div>

| Delaware                                 |     |         20-8121647 |
| (State or other jurisdiction of          
 incorporation or organization)           |     |      -IRS Employer 
 Identification No. |
| 25 Hartwell Avenue                       
 Lexington, MA                            |     |              02421 |
| (Address of principal executive offices) |     |          -Zip code |

<div align='center'>Rapid Micro Biosystems, Inc. 2021 Incentive Award Plan

Rapid Micro Biosystems, Inc. 2021 Employee Stock Purchase Plan</div>

#### Rapid Micro Biosystems, Inc. 2023 Inducement Plan
<div align='center'>(Full title of the plan)</div>

#### Robert Spignesi

#### President and Chief Executive Officer

#### Rapid Micro Biosystems, Inc.

#### 25 Hartwell Avenue

#### Lexington, MA 02421
<div align='center'>(Name and address of agent for service)

(978) 349-3200

(Telephone number, including area code, of agent for service)</div>

<div align='center'>Copy to:</div>

#### Edwin O'Connor, Esq.

#### Adam Johnson, Esq.

#### Goodwin Procter LLP

#### 620 Eighth Avenue

#### New York, NY 10018
<div align='center'>(212) 813-8800</div>

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

| Large accelerated filer |     | ¨ |     | Accelerated filer         |     | ¨ |
| Non-accelerated filer   |     | x |     | Smaller reporting