The school announced Cosgrove agreed to a three-year contract extension, which ties him to Maine through June 2016.
"Jack has done a terrific job as the leader of the Black Bear football team," Athletic Director Steve Abbott said. "He thrives on the intense competition and rivalries in the Colonial Athletic Association and is committed to continuing to build upon the team's success."
Cosgrove, 56, played quarterback for Maine (1974-77) and has been on the football coaching staff nearly every season since. He has been head coach since 1993.
The Black Bears' 5-6 record last season pushed his career mark to 111-118. The win total is a Maine record.
The Black Bears have been to the NCAA playoffs four times, most recently in 2011, under Cosgrove and the team won CAA titles in 2001 and 2002.