A Queensland State of Origin representative half, he played his club football in Australia with Canterbury-Bankstown (with whom he won the 1988 and 1985 premierships) and Newcastle (whom he captained), as well as in England with Halifax.

[2] With Mortimer retiring, Hagan might have had a chance for a permanent position in the halves, but by this time he had already decided to move to Newcastle where he signed with the Knights.

[2] Hagan's craft and guile at five-eighth led to a rapid rise in the Knights' fortunes: they advanced from fourteenth to sixth (losing a play-off for the club’s first finals berth) in two seasons between 1988 and 1990.

During his career with Newcastle, Hagan played five State of Origin games for Queensland, deputising for Allan Langer at halfback in 1989.

In early 2006, Hagan signed a contract to coach the Parramatta Eels from 2007 to 2009, finishing his tenure at Newcastle at the end of the 2006 season.

In 2007, the Eels showed much improvement under Hagan, spending much of the season at 3rd position on the ladder (only behind the Melbourne Storm and bitter rivals the Manly-Warringah Sea Eagles) before a surprise defeat against his old club the Newcastle Knights (who were at the time coached by Brian Smith) triggered a late-season form slump.

Following a relatively disappointing 2008 season, Michael Hagan ended his head coaching role at the Parramatta Eels citing family reasons and health.