After an outstanding amateur career Michael turned Professional in 2006 where he competed on the PGA Tour of Australasia finishing second in his first start on the Tour. He also spent the year competing on the Web.com Tour where he earned enough money to qualify for the PGA TOUR in 2007.
His first season on the main Tour was late to start due to a stress fracture, this resulted in Michael being given a medial exemption for the 2008 season. Unable to retain his card, Michael returned to the Web.com Tour in 2009. Recording three victories on the Web.com Tour he earned a battle field promotion back to the PGA TOUR. 2009 was an outstanding season for Sim who also competed in the U.S. Open and PGA Championship.
He brought this form home to Australia and won the PGA Tour of Australasia Order of Merit and finished the year ranked inside the top-50 in the World. This earned him a start in the 2010 Masters but was forced to withdraw with injury.
Michael claimed three top-5 finished on the PGA TOUR in 2010 and retained his card for 2011. After another injury plagued season, Sim returned to the Web.com Tour in 2012, finishing 139th on the money list. Since then he has played limited golf on the PGA Tour of Australasia and OneAsia.
Recently Michael has been playing on the Tour of Australasia, European Tour and the Web,com Tours. Finishing 16th at the Fiji International. In October, Michael won the Isuzu Queensland Open scoring a birdie on the last hole to claim his first title on Australian soil.
- Represented Australia at the Eisenhower Trophy in 2004.
- Highest ranked amateur in the world in 2005.
- In 2009 he earned a battlefield promotion on to the PGA TOUR after winning three tournaments in one season on the Web.com Tour.
- Has predominately played on the Web.Com Tour and the Tour of Australasia Tour in 2017
- 2017 Isuzu Queensland Open Champion