Company: ARMP
Filing Date: 2025-08-13
Form Type: S-8
Source: 0001104659-25-077650
Chunk: 0

Company: Armata Pharmaceuticals, Inc.
Filing Date: 2025-08-13
Form: S-8
Chunk 0
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<div align='center'>UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-8

REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933

ARMATA PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its
charter)</div>

| Washington                      | 91-1549568         |
| (State or other jurisdiction of 
 incorporation or organization)  | -I.R.S. Employer   
 Identification No. |

<div align='center'>5005 McConnell Avenue

Los Angeles, CA 90066

(Address of Principal Executive Offices) (Zip
Code)

Armata Pharmaceuticals, Inc. 2016 Equity Incentive Plan

Armata Pharmaceuticals, Inc. 2016 Employee Stock Purchase Plan

(Full titles of the plans)

Armata Pharmaceuticals, Inc.

5005 McConnell Avenue

Los Angeles, CA 90066

(Name and address of agent for service)

(310) 655-2928

(Telephone number, including area code, of agent
for service)

Copies to:</div>

| Deborah L. Birx              
 Armata Pharmaceuticals, Inc. 
 5005 McConnell Avenue        
 Los Angeles, CA 90066        
 (310) 655-2928               | Jared Fertman                 
 Willkie Farr & Gallagher LLP  
 787 Seventh Avenue            
 New York, New York 10019-6099 
 (212) 728-8000                |

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,” “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 company | x |
|                         |   |     | 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 7(a)(2)(B) of the Securities Act.¨

<div align='center'>EXPLANATORY NOTE
REG