He made his League of Ireland debut for Athlone Town on 4 March 1979. During his time at St Mels Park he was twice top scorer in the League of Ireland in 1981/82 and 1984/85 . Is the all time leading scorer for Athlone.
On 25 February 1981, he played for Republic of Ireland U21 at Anfield.
Signed for Shamrock Rovers in October 1985 and made his debut in a 3-0 win over Bohemians on the 27th. He scored his first goal for the Hoops on the 17th of November at Home Farm. Played in a memorable friendly win over Arsenal in February 1986 when his fellow Athlone man and ex teammate Noel Larkin scored the winner. He played no part of the 1986/87 season due to a broken leg. Made 1 appearance in the European Cup in September 1987.
Left in October 1987 to sign for his brother Turlough O'Connor at Dundalk where he stayed for one season before returning to his hometown club.
In May 1992 he was appointed player manager of Ireland's oldest club
In his second season he guided them to promotion.
In May 1995 he scored the decisive penalty to keep Athlone in the Premier Division
However they got relegated by penalties the following year with Michael retiring as a player and resigning as manager. Athlone have languished in the First Division since then.
He was appointed manager again for a second spell for the 2006 season. His first game in charge was also the clubs first game at their new stadium in Lissywoollen but he resigned in July 2007
The O'Connor name is synonymous with Athlone Town as another brother Padraig O'Connor played for the club.