Originally from Bendigo, Victoria, where he attended Catholic College Bendigo, Selwood was recruited from the Bendigo Pioneers with the West Coast Eagles' fourth pick and number 22 overall in the 2007 AFL Draft. He made his debut against Fremantle in the Round 3 Western Derby in 2008. He was retained in the team for the Round 4 match against the Sydney Swans, but was dropped after a poor performance, obtaining only nine possessions. He played several further games later in the season, however.
Selwood became a regular in the Eagles' line-up over the following three seasons, initially as a tagger, and later as an inside midfielder. He continued his outstanding form throughout the 2012 season, playing predominantly as a tagger and midfielder depending on the opposition. He capped off a stellar season by winning the West Coast Eagles club champion award, ahead of team mates Dean Cox and Shannon Hurn.
Selwood along with brother Adam and teammates such as Luke Shuey and Ashton Hams have been criticised by AFL commentators and coaches, and then eventually AFL fans, for supposedly 'ducking' in tackles to get free kicks. Selwood and his teammates have received some support from the AFL community, AFL boss Andrew Demetriou and their coach John Worsfold who all agree that there have not been rule breeches in this area by these players.