Born in San Ramon, California, Matthews and his family moved to Scottsdale, Arizona when Matthews was an infant. He learned to play hockey in Arizona, developing an interest after watching the local Phoenix Coyotes play.
Internationally, Matthews has represented the United States in numerous tournaments including a U17 WHC gold medal, two U18 WJC gold medals, and two IIHF World U20 Championship appearances.
Matthews was born in the San Francisco Bay Area to Brian, from California, and Ema, originally from Hermosillo, Mexico. Matthews began attending Phoenix Coyotes games when he was two years old, and his favorite players were Shane Doan and Daniel Brière. Initially, Matthews didn't have much interest in the sport, but was captivated by the Zamboni machine that cleaned the ice during intermissions. Matthews first expressed a desire to play hockey shortly after his fifth birthday, and began playing with the Arizona Bobcats minor hockey program. When Matthews was younger, he played both hockey and baseball. According to his father, baseball was his best sport, with his incredible hand-eye coordination making him an excellent hitter. However, he hated the slow pace of the game, preferring the fast pace and constant action of hockey. When he first started playing hockey, his parents knew almost nothing of the sport.
Matthews lived with his mom and sister Alexandria while playing with the ZSC Lions in Switzerland, while his father remained in Arizona, though they talked over the phone daily. She typically cooked him breakfast and dinner, with lunch usually being a team affair occurring after a practice. Off the ice, Matthews is enrolled in some online courses with the University of Nebraska Omaha, and received homework help from his sister while in Switzerland. In late August, 2016, he moved to Toronto and began working out with teammates Mitchell Marner and Morgan Rielly.
Matthews was drafted 57th overall by the Everett Silvertips in the 2012 WHL Bantam Draft but opted to play for the United States National Team Development Program, who play in the junior United States Hockey League (USHL). That season he played for the U.S. National U17 Team (USDP) where he gained national attention from NHL scouts, even being featured on the NHL website with emphasis put on his unique southwestern background. In his second season with the U.S. National U18 Team (USDP), Matthews finished first in league scoring with 116 points (55 goals, 61 assists), breaking the National Team Development Program record of 102, set by Chicago Blackhawks star Patrick Kane in 2005–06 and besting Buffalo Sabres' Jack Eichel by 29 points. On May 21, 2015, Matthews won the USA Hockey Bob Johnson Award for excellence in international competition.
Matthews trained with the USA Hockey National Team Development Program team during the 2013–14 and 2014–15 seasons. Matthews was named the 2015 Most Valuable Player at the World U18 Championships in addition to being named to the IIHF All-Star Team, and named the IIHF Best Forward after finishing as the tournament's top scorer.
Rather than continue in US amateur hockey, or play in Canadian junior leagues, Matthews chose to play professionally for his last season before he was eligible for the 2016 NHL Entry Draft, having missed the 2015 NHL Entry Draft cutoff date of birth by two days. On August 7, 2015, Matthews signed a one-year contract to play in the Swiss National League A for the ZSC Lions. Matthews was approached by Lions head coach Marc Crawford, who was awed by his skating and puck possession while scouting the U18 Championships. Crawford quickly called Matthews' agent, Pat Brisson, to discuss the proposal of signing the player to his team. Matthews and his family quickly bought in once the tournament had ended, and they spent the next few months applying for various paperwork. After missing the first four games of the 2015–16 regular season, he made his NLA debut on September 18, 2015, and scored his first goal that same day against Benjamin Conz of HC Fribourg-Gottéron on home ice at the Hallenstadion. He would spend most of the season on a line with Robert Nilsson, finding chemistry with the veteran forward.
On February 3, 2016, he tallied two assists in a 4–1 win over the Lausanne HC in the 2015–16 Swiss Cup final. Matthews finished the 2015–16 regular season as the second top scorer on the Lions and tenth in the NLA. His 1.28 points-per-game average was second in the league, behind only Pierre-Marc Bouchard. Moreover, he also won the NLA Rising Star Award, and was second to Bouchard in voting for Most Valuable Player. Matthews' stint in the NLA ended earlier than expected when the top seeded Lions got swept in the first round of the 2016 playoffs by the SC Bern, the eventual league champions.
In late June, Matthews was selected first overall in the 2016 draft by the Toronto Maple Leafs, becoming the first American to be picked with the top selection since Patrick Kane in 2007. He had been widely expected to go first overall for over a year leading up to the event, consistently topping prospect charts and major scouting reporters. Media speculation suggested that Matthews and the team had engaged in a minor contract dispute over the issue of performance bonuses; Matthews was asking the team for a contract similar to that of Connor McDavid or Jack Eichel, which were both valued at $3.775 million annually (with all bonuses factored in). Although Maple Leafs general manager Lou Lamoriello has been very open over his disapproval of including bonuses in player contracts in the past, he was very clear in stating that performance bonuses were never an issue while discussing Auston's contract. It is widely expected that first overall selections, as well as any other highly touted early draft picks, receive the maximum entry-level compensation under the NHL's Collective Bargaining Agreement. Lamoriello had previously been involved in a contract dispute while in New Jersey with 4th overall pick Adam Larsson over the issue of bonuses. Larsson came out of negotiations without any performance bonuses attached to his entry-level deal. On July 21, the two parties finalized a deal, with Matthews inking a three-year entry-level contract, which included the maximum allocation of performance bonuses. Lamoriello would go on to state that the contract was agreed upon within 10 minutes of sitting down with Matthews' agent Pat Brisson, and that the deal was done "the Toronto way." Brisson would later confirm that the two parties did not have any issues ironing out the deal. The contract was identical in value to those McDavid and Eichel had secured a year earlier. Two weeks later, Matthews was given the NLA Youngster of the Year award, which is reserved for the league's top rookie. It would be his fifth award from his stint in Switzerland.
Matthews made his NHL debut in the Maple Leafs' first game of the season on October 12, 2016, against the Ottawa Senators. He scored four goals in the game, all against Craig Anderson. This was the first time in modern NHL history a player scored four goals in his debut; previously Joe Malone and Harry Hyland scored five goals each in their NHL debuts on December 19, 1917 (the first game in the history of the NHL). Four others had scored three goals since then, though none had surpassed a hat trick since Matthews. Matthews' jersey would go on sale following his debut, where it quickly became the highest selling sweater in the league. Two months later in the NHL Centennial Classic, Matthews scored the game-winning goal in overtime, securing a 5–4 victory for the Maple Leafs. On March 28, 2017, Matthews scored his 35th goal of the season, beating Wendel Clark's previous record for most goals in a season (34) by a Leafs' rookie April 3 saw Matthews score his 39th goal and 67th point, breaking the franchise record for most points in a season as well as the record for most goals by an American born rookie. A few days later he notched his 40th goal of the season, becoming the second rookie since the 2004–05 lockout to reach the milestone and only the fourth teenager in league history to do so. He would finish the year with 40 goals, good enough for second most in the league. Matthews' play assisted the Maple Leafs in making the playoffs for the first time in a full season since 2004, where the team took on the top seeded Washington Capitals in the first round. After going pointless in the first two games of the series, Matthews scored in each of the last four games as the team was eliminated in six contests by the Capitals. His four consecutive games with a goal marked the first time since 1986 where a teenager scored in four straight playoff games, with Maple Leafs alumnus Wendel Clark being the only other player in league history to accomplish the feat. In recognition for his historic accomplishments throughout the year, Matthews was awarded the Calder Memorial Trophy, as the league's top rookie, with 164 of 167 first-place votes.
Matthews helped lead the American national hockey team to gold at the U18s in 2014. He did so again in 2015, leading the tournament in scoring and being named MVP, as well as earning the top forward slot on the Media All-Star team. He was also named to the roster for the 2015, but was forced to pull out of the tournament due to a back injury.
At the 2016 IIHF World Junior Championships held in Helsinki, Matthews and Matthew Tkachuk each scored eleven points to lead the American team in scoring. After losing in the semifinals, the American team beat Sweden to claim the bronze medal. His seven goals was one shy of Jeremy Roenick's Team America record of eight, which was set in 1989. In recognition of his play, he was named to the tournament All-Star Team. Later that year, Matthews played with the US national men's team for the 2016 IIHF World Championship tournament, where he led the team in scoring. A few months later, Matthews was announced as a member of Team North America for the 2016 World Cup of Hockey. Matthews began the pre-tournament games playing left wing on the third line, playing alongside Ryan Nugent-Hopkins and Nathan MacKinnon. After impressing, he began the tournament on the top line with Connor McDavid. The two back-to-back first overall picks found chemistry but were unable to help North America to a medal finish. Matthews finished the tournament with three points in three games played. He was advised by the Maple Leafs to skip the 2017 IIHF World Championship and instead rest.
Matthews comes from a family of athletes, with his father having played college baseball and with an uncle, Wes Matthews, who played in the NFL. The family moved to Scottsdale, Arizona when Auston was two months old. His father is the chief technology officer of a manufacturing company based in New Jersey, spending most of his time telecommuting from Arizona. He has two sisters, Alexandria, who is three years older, and Breyana, who is five years younger. Thanks to his mother's heritage, Matthews can speak some Spanish.
His favorite athlete growing up was Kobe Bryant, while his favorite sports movie is The Mighty Ducks. Matthews, a big fan of players Jonathan Toews and Anže Kopitar due to their all around offensive and defensive game, has had his playing style compared to them.Most goals scored in an NHL debut in the modern era (four goals), surpassed Alex Smart, Real Cloutier, Fabian Brunnstrom and Derek Stepan (three goals).
Most goals by an American born rookie, surpassing Neal Broten who scored 38 goals in his rookie season with the Minnesota North Stars in the 1981–82 season
Fastest Maple Leafs player to score 25 goals (52 games), surpassed Howie Meeker (58 games in 1946–47).
Most points by a rookie, surpassed Peter Ihnačák, who had 66 in the 1982–83 season
Most goals by a rookie, surpassed Wendel Clark, who had 34 in the 1985–86 season