He first appeared on the TV series The Miraculous Mellops. He has since appeared as Campbell Todd on the Australian TV series Always Greener, starred in the mini-series Marking Time and starred and directed the 2003 film Ned. He also directed and starred in a parody of The Matrix called Computer Boy. Forsythe has also written a number of acclaimed sketches for the late night Sketch comedy series Comedy Inc - The Late Shift. He also starred in the Australian/British television series co-production Tripping Over.
In 2009, Forsythe wrote and directed the Tropfest short Being Carl Williams. The short won second prize and the Best Comedy award. The 2010 Tropfest saw him win first prize with Shock, a short tribute to radio personality Kyle Sandilands.
In 2012 he played a lead role in one of Australia's most popular TV mini-series ever. Forsythe played John Cornell in the Australian drama Howzat! Kerry Packer's War which was based on Packer's takeover of cricket in 1977, and the establishment of World Series Cricket.
Forsythe was married to Helen Dallimore, star of the musical Wicked. They separated in 2013.
