Austin was born in New York City, the son of Giny Rodriquez Toranzo and Joe Szymanski. His middle initial, "T", is taken from his mother's maiden name. His mother is of Puerto Rican, Argentine, and Spanish descent, and his father is of Polish, Irish, and English ancestry. Austin embraces his Puerto Rican heritage, though he has said that he is not fluent in Spanish. He has a younger sister, Ava.
Austin's career began in 2002 when he appeared in commercials. A year later, he appeared in his first credited acting role as Kid 1698 in a comedy sketch on The Late Show With David Letterman. In 2004, he landed his first major role – voicing Diego, the cousin of Dora, on the hit Nickelodeon animated series Dora the Explorer. He continued to voice Diego on the spin-off series, Go, Diego, Go!, for three seasons. Along with voicing Diego, Austin was cast in multiple voice roles for the feature films The Ant Bully and Everyone's Hero – he was also cast in the Comedy Central special Merry F#%$in's Christmas. In 2006, Austin landed the lead role of Angel Macias in his first live-action feature film, The Perfect Game, which was based on a true story about the first non-U.S. team to win the 1957 Little League World Series. The film wouldn't be released in the United States until more than three years later due to post-production financing difficulties.
2007–11: Wizards of Waverly Place
Austin appeared in his first Walt Disney Company production in 2007 when he portrayed the role of Chris in the Disney Channel original film Johnny Kapahala: Back on Board. Later that same year, he was cast as Max Russo in the Disney Channel series Wizards of Waverly Place. He played the youngest sibling of a wizarding family, co-starring with Selena Gomez and David Henrie. Until the end of Wizards of Waverly Place in 2011, Austin appeared in multiple Disney productions. In the summer of 2009, he played the role of Max Russo in the Wizards on Deck crossover episode which included two other popular Disney shows, The Suite Life on Deck and Hannah Montana.
During the same summer, he starred in the made-for-television film Wizards of Waverly Place: The Movie. The film was a rating hit, becoming the second most-viewed Disney Channel film at that time, behind High School Musical 2. It was also the #1 scripted telecast of 2009. Austin made his live-action feature film debut in 2009 with the role of Bruce, an orphan who hides numerous dogs in an abandoned hotel, in the DreamWorks film Hotel for Dogs. In the fall of 2010, Austin was named as one of the "25 Brightest Latino Stars Under 25" by Latina magazine. He has written and sold his first screenplay, Kings of Suburbia, which he has said is written in the same vein as his favorite film Stand By Me.
2011–2015: The Fosters
In 2011, Austin voiced the role of Fernando, an orphaned Brazilian boy who is forced to capture exotic birds, in the 20th Century Fox animated musical film Rio. He reprised the role in the sequel, Rio 2. He was also in the romantic-comedy film New Year's Eve, released in December 2011. The following year, he had guest roles on the Lifetime comedy-drama Drop Dead Diva as Samuel Forman, a 16-year-old multimillionaire, and on the NBC legal drama series Law & Order: Special Victims Unit as Rob Fisher, the boyfriend of a girl whose family is massacred.
Austin landed his next major role in 2013 when he was cast as Jesus Foster in the ABC Family family/teen drama series The Fosters. The series tells the story of two moms raising both biological and foster children in a "multi-ethnic" household in San Diego, California. He played Jesus for two seasons until he left the show in the second-season finale in 2015. In a statement on his departure, Austin said: "I'm honored to have been a part of such a groundbreaking series ... Thank you for letting me be a part of your family, it's been a pleasure." His role was recast for the third season, with Noah Centineo.
In 2016, he provided the voice for Jaime Reyes / Blue Beetle in the DC Comics animated direct-to-video film Justice League vs. Teen Titans. On August 30, 2016, Austin was revealed as one of the contestants who would compete on season 23 of Dancing with the Stars. He was partnered with professional dancer, Jenna Johnson. On September 20, 2016 Austin and Johnson were announced as the first couple to be eliminated from the competition. In October 2018, it was announced that Austin joined the cast of Adverse, a neo-noir thriller starring Mickey Rourke. The movie is slated to release theatrically in 2019.
Austin divides his time between living in Los Angeles and New York. He has two dogs, Bogey and Beju. His family owns a historic restaurant called The Clarksville Inn. The restaurant, located in West Nyack, New York, originally opened in 1840 as a hotel.
Austin devotes time to various charitable causes including the Make-A-Wish Foundation, which grants wishes to children who have life-threatening medical conditions; the Starlight Children's Foundation, which is dedicated to improving the quality of life for children with chronic and life-threatening medical conditions; and Variety's Power of Youth initiative, which partners with young stars to help raise money for their chosen causes. He's also supported the Boys & Girls Clubs of America, stating “I know how important it is to have a supportive environment and feel good about yourself, especially as an adolescent.”