[7][8] After playing State basketball for Victoria Country, he attended the Australian Institute of Sport (AIS) in Canberra for three years.

[12] Sources: Dellavedova was recruited by Randy Bennett and the Saint Mary's College of California in 2009 and signed with the Gaels before the 2009–10 season.

[16] That season, the Gaels won 28 games and reached the Sweet Sixteen of the 2010 NCAA men's basketball tournament.

[17] On 16 January 2013, Dellavedova scored 18 points, including a game-winning three-point buzzer-beater, in a 70–69 victory over the BYU Cougars.

[20] He finished his college career as Saint Mary's all-time leader in scoring, assists, games played, free throw percentage, and three-point shots.

Dellavedova's #4 was the second retired by the school's men's basketball program, joining Tom Meschery in the rafters of McKeon Pavilion.

[38][39] Following the Cavaliers' Game 3 win over the Atlanta Hawks in Eastern Conference Finals, Dellavedova's aggressive play became a major talking point with some describing him as a "dirty" player.

Despite this criticism, teammate LeBron James and NBA great Charles Barkley both defended Dellavedova's style of play.

[41] In Game 2 of the NBA Finals against the Golden State Warriors, in the absence of the injured Kyrie Irving, Dellavedova held Stephen Curry to 0-of-8 shooting and four turnovers while guarding him.

[44][45] In Game 3, Dellavedova scored a playoff career-high 20 points as the Cavaliers defeated the Warriors to take a 2–1 series lead.

[46] After the game, Dellavedova was so dehydrated that he needed an IV,[47][48] and he was quickly taken to the Cleveland Clinic for medical attention.

[56] In a Finals rematch with the Golden State Warriors, the Cavaliers became the first team in NBA history to win the championship after being down 3–1 in the series.

[52] Dellavedova made his debut for the Bucks in their season opener on 26 October 2016, scoring 11 points in 29 minutes as a starter in a 107–96 loss to the Charlotte Hornets.

[66] A right ankle sprain suffered on 4 February against the Nets[67][68] saw Dellavedova miss 29 straight games, returning to action in the Bucks' regular-season finale against the Philadelphia 76ers on 11 April.

[69] On 7 December 2018, Dellavedova was acquired by the Cleveland Cavaliers in a three-team trade that also involved the Bucks and the Washington Wizards.

[74] He appeared in just 13 games with the Cavaliers during the 2020–21 season as he suffered a variety of ailments, including a concussion, whiplash, an emergency appendectomy, and a neck strain.

However, multiple current and former players have spoken in defense of Dellavedova, including LeBron James,[13] Kobe Bryant,[85] Charles Barkley,[40] and Antonio Davis.

[87] He was named in the Australian senior national team, the Boomers, to compete for the first time at the 2009 FIBA Oceania Championship.

[102][103] On 28 March 2015, Dellavedova escorted Jackie Custer, a 17-year-old cancer patient, to Akron Children's Hospital's "A Prom to Remember" event.