D. Mullen transfers
| Date | Type | From | To |
|---|---|---|---|
| 2026-01-01 | Free agent |  Derry City DER |  Dundalk DUN |
| 2025-12-30 | Free agent | Derry City DER | Dundalk DUN |
| 2023-07-06 | Free |  Partick PAR | Derry City DER |
| 2020-08-04 | Free |  ST Mirren MIR |  Dundee DUN |
| 2018-01-11 | N/A |  Livingston LIV | ST Mirren MIR |
| 2017-12-12 | Loan | Livingston LIV | ST Mirren MIR |