From 1999 to 2003 he appeared 87 times in the Norwegian top flight with Stabæk, scoring 12 goals.

[4] After his retirement as active footballer in 2012, Michelsen became Geir Bakke's assistant coach at Kristiansund.

In 2016, Michelsen led his team to promotion to the 2017 Eliteserien, which was Kristiansund BK's first season in the top division of Norwegian football.

Kristiansund finished in fifth place in the 2018 season, an achievement that led to a Coach of the Year nomination for Michelsen.

[5] On 4 July 2019, Kristiansund announced that Michelsen had signed a contract extension which will keep him at the club till the end of the 2023 season.