The red-headed O'Brien used to make 10-hour return car trip to Glenelg to play under-15 games. At 16 he played in his first West Gambier senior premiership in the Western Border league. West won again the following year with O'Brien playing in the ruck. He has a terrific mark and good leg speed, where he recorded the third-best result in agility draft camp.[1]
AFL career
Hawthorn selected O'Brien with pick 28 in the 2012 AFL Draft.
He spent 2013 developing in the VFL playing for Hawthorn's reserve affiliate side, the Box Hill, and was a member of their premiership winning side.
Entering into his second season, O'Brien changed from number 40 to Hawthorn's famous number 23 guernsey previously worn by Lance Franklin following the latter's move move to Sydney at the end of the 2013 season.[2]
On August 22, 2017, after having a career-best season, O'Brien signed a two-year contract extension keeping him at Hawthorn until the end of 2019.[3]
At the end of the 2021 AFL season, O'Brien exercised his rights as a free agent and joined the Western Bulldogs.[4] He played for the Bulldogs for two seasons, before being delisted in September 2023.[5]
^The 2020 season was played with 17 home-and-away matches per team (down from 22) and 16-minute quarters with time on (down from 20-minute quarters with time on) due to the impact of the COVID-19 pandemic.