Austin attended Poway High School in Poway, California. In 2009, as a senior, he hit .390 with five home runs and 37 RBIs. After graduating and going undrafted in the 2009 MLB draft, he enrolled and played college baseball at Fresno State University. In 2012, he played Collegiate Summer baseball with the Bourne Braves of the Cape Cod Baseball League. As a senior in 2013, he batted .279 with three home runs and 24 RBIs in 53 games. He was drafted by the Baltimore Orioles in the tenth round of the 2013 Major League Baseball draft. He signed and spent 2013 with the Aberdeen IronBirds, posting a .235 batting average with 21 RBIs in 54 games. In 2014, he played for both the Delmarva Shorebirds and Frederick Keys, batting a combined .251 with one home run and 37 RBIs in 90 total games between the two teams, and in 2015, he played for Frederick and the Bowie Baysox, compiling a .280 batting average with three home runs and 31 RBIs in 78 total games. Austin spent 2016 with Bowie, Frederick, and the Norfolk Tides, hitting at .287/.336/.416 with six home runs and 34 RBIs in 80 games between the three clubs.
After the 2016 season, Austin played in the Arizona Fall League. He played the 2017 season with the Bowie BaySox where he batted .281 with ten home runs and 46 RBIs in 105 games. The Orioles added him to their 40-man roster after the 2017 season.
Austin made his Major League debut in 2018 for the Baltimore Orioles. He spent 2019 between triple a Norfolk and Baltimore. He spent 2020 at the alternate training site for the Orioles. Austin is currently under contract with the Orioles heading in to the 2021 season.