He has previously played in Major League Baseball (MLB) for the New York Yankees, Minnesota Twins, San Francisco Giants, and Milwaukee Brewers.

Austin played baseball for Heritage High School in Conyers, Georgia, before the Yankees selected him in the 2010 MLB draft.

[5] In 2008, his sophomore season, Austin had a .626 batting average with 19 home runs, and The Rockdale Citizen named him the high school baseball hitter of the year.

He had surgery to remove the tumor, but did not require chemotherapy as the cancer was caught early and did not spread to other parts of his body.

[16] Brian Cashman, the Yankees' general manager, referred to Austin as a "mega prospect" in August 2012.

[22] The Yankees assigned him to the Scottsdale Scorpions of the Arizona Fall League (AFL) after the regular season.

[24] After the regular season, the Yankees again assigned Austin to Scottsdale in the AFL,[25] but his playing time was limited by a knee injury.

[29] The Yankees designated him for assignment at the end of the minor league season in September, removing him from their 40-man roster.

[39] The Yankees promoted Austin to the major leagues on June 24, after designating Chris Carter for assignment.

[42] On August 19, Austin hit a three-run homer off Boston Red Sox ace Chris Sale which helped them win a major game in a pennant race.

[43] On April 11, 2018, against the Red Sox at Fenway Park, Austin was hit by a pitch from Joe Kelly in possible retaliation for spiking Brock Holt earlier in the game.

Austin then slammed his bat into the dirt in anger and charged the mound, causing a bench-clearing brawl.

[46] On July 30, 2018, the Yankees traded Austin and Luis Rijo to the Minnesota Twins for Lance Lynn.

[47] The Twins assigned him to the Rochester Red Wings of the International League, whom Scranton was playing at the time.

On April 6, 2019, Austin was designated for assignment following the selection of Chase De Jong’s contract.

[55] After he batted .333 with four home runs and 10 RBIs in 15 games for San Antonio, the Brewers promoted Austin to the major leagues on September 1.

On November 15, 2019, Austin signed a one-year contract with the Yokohama DeNA BayStars of Nippon Professional Baseball.

He would end up winning the NPB batting title, edging out Tokyo Yakult Swallows outfielder Domingo Santana's .315 average.

[59] On July 2, 2021, Austin was named to the roster for the United States national baseball team for the 2020 Summer Olympics, contested in 2021 in Tokyo.

[61] Austin co-designed a logo that has been printed on T-shirts, with the proceeds of the sales going to the Sean Kimerling Testicular Cancer Foundation.