| Church: | Church of Constantinople |
| Archbishop Of: | Ecumenical Patriarch of Constantinople |
| Term: | 21 May 1320 - 19 April 1321 |
| Predecessor: | John XIII of Constantinople |
| Successor: | Isaias of Constantinople |
| Birth Date: | ? |
| Death Date: | 19 April 1321 |
Gerasimus I (Greek: Γεράσιμος, Gerasimos; died 19 April 1321)[1] was the Ecumenical Patriarch of Constantinople from 1320 to 1321.[2]
He was born in Philadelphia and became abbot of the prestigious Mangana Monastery in Constantinople. He was elected as patriarch at an advanced age, and died on 19 April 1321.
He became Patriarch during the reign of Emperor Andronicus the Second; the Emperor found him to be 'docile'.[3]