Recruited from Temora, New South Wales, Breust played both rugby league and Australian rules football as a junior but turned his focus to Australian rules from age 14.[2] Breust played football and basketball with Isaac Smith in Temora before the latter moved to Wagga Wagga when he was 13, with both ending up at Hawthorn where they played together in the 2013 AFL Grand Final.
Before being drafted at the age of 18, Breust played as a member of the NSW/ACT Rams.
He was drafted by Hawthorn with selection 47 in the 2009 AFL Rookie Draft in December 2008.
Breust fractured his left tibia during 2008, but after recovering from that injury he received an invitation to trial with the Hawks and was then selected in the draft.[3]
Breust improved more during the 2012 AFL season, particularly with his five-goal effort in Hawthorn's eight-goal win over Collingwood. He played predominantly as a forward, but had short bursts in the midfield throughout the year. Breust played in Hawthorn's losing Grand Final team. At the end of the year, he placed fourth in the Peter Crimmins Medal behind winner Sam Mitchell.
In 2013, Breust kicked a goal in the last quarter of the AFL Grand Final against the Fremantle Dockers to win his first AFL Premiership.
In 2014, Breust began a streak of 29 consecutive goals without scoring a behind, tying with the record set by Tony Lockett in the 1995 season. The streak began during the last quarter of Round 5 against the Geelong Cats and was broken in Round 17 against the Adelaide Crows.
In Round 21, 2017, Breust kicked his 300th career goal in a 27-point victory over North Melbourne. Breust was widely regarded as having a below average 2017 season, kicking only 33 goals, his second-lowest annual tally to that date, just surpassing the 30 goals in his debut season.[6]
Breust had a below-average 2019. Without tall marking targets around them, his combination in the forward line with Jack Gunston was seen as being rather ineffective, with the pair kicking just 60 goals between them, as opposed to 105 the previous season.[9]
On 18 February 2023, Breust was announced as co-vice captain of Hawthorn Football Club alongside fellow small forward Dylan Moore to support newly announced captain James Sicily.[10]
Round 12 2023 Breust kicked his 500th career goal in the brown and gold against Port Adelaide.
^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.
