He was selected by Essendon with the 47th selection in the 2001 AFL Draft. He is a backline player who has played halfback or back pocket for much of his career. However, lately he has developed his game to play as a tagging-defensive midfielder.
He is a very quick player and runs off half back very well. A knee injury in 2005 sidetracked his career a little, but he has made a strong comeback in defence during 2006. In 2007 and 2008 his role changed, and he played primarily as a defensive forward and defensive midfielder respectively.
In October 2011, Welsh retired from Essendon Football Club due to several injury setbacks after playing 162 games with the club.