Exhibit 31.1
Certification of Principal Executive Officer
I, Jeffrey M. Dayno, certify that:
| 1. | I have reviewed this Annual Report on Form 10-K/A of Harmony Biosciences Holdings, Inc.; and | 
| 2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report. | 
| Date: | February 28, 2024 |  | |
| By: | /s/ Jeffrey M. Dayno |  | |
|  |  |  | |
| Name: | Jeffrey M. Dayno |  | |
|  | President, Chief Executive Officer and Director (Principal Executive Officer) |  | |