Hinkley, recruited from Camperdown, started his league career as a forward at Fitzroy but played his best football with Geelong, where he was used as a rebounding defender. Hinkley walked out of Fitzroy in 1988 and asked for a clearance to Geelong. He stood out of football for the rest of 1988 season before being trade to Geelong for the 1989 season. A half back flanker in the 1991 and 1992 All-Australian teams, Hinkley also won a Carji Greeves Medal as Geelong's best and fairest player in the 1992 AFL season. In the same year he finished third at the Brownlow Medal count, behind winner Scott Wynd and Hawthorn's Jason Dunstall. He appeared in 12 finals with Geelong, including the 1992, 1994 and 1995 Grand Final losses.
Retiring after the 1995 AFL Grand Final, Hinkley joined Hampden Football League club Mortlake as coach, where he remained for three seasons. He then returned to Camperdown and steered his former club to back to back premierships in 1999 and 2000, the former as captain-coach. St Kilda acquired his services as an assistant coach in 2001 but the following year he took up the role of senior coach of Bell Park in the Geelong Football League and oversaw a premiership in 2003. He resumed his AFL coaching career in 2004, as an assistant to Mark Thompson at Geelong. At the end of the 2009 season, Hinkley was announced as an assistant at the new Gold Coast Suns Franchise. Hinkley has also interviewed for the Richmond, Geelong and St Kilda senior coach positions but was unsuccessful.
On 8 October 2012, Hinkley was announced as the senior coach of the Port Adelaide Football Club making him the first coach that has not been associated with the club before since Fos Williams. In his debut season, he led Port to 13 wins, which included an elimination final win at the MCG against Collingwood before being eliminated by Geelong in a close game a week later. This came to a surprise to many as Port Adelaide had only won eight games in the previous two seasons combined. For his impressive season, Hinkley was voted as the Coach of the Year by the AFL Coaches Association.
A year later, despite predictions by many that Port Adelaide would miss the finals, Hinkley led the club to a preliminary final finish; having finished the minor rounds in fifth place on the ladder, the Power defeated Richmond and Fremantle in their first two finals before losing to eventual premiers Hawthorn.