Exhibit 31.3
Certification of Principal Executive Officer
I, Timothy P. Walbert, certify that:
| 1. | I have reviewed this Amendment No. 1 to the quarterly report on Form10-Q/A of Horizon Pharma plc; 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: September 28, 2017 |
/s/ Timothy P. Walbert |
| Timothy P. Walbert |
| Chairman, President and Chief Executive Officer |
| (Principal Executive Officer) |
