[3] His father won a CCAA national championship, playing for the Southern Alberta Institute of Technology, and later coached at the high school, college, and professional levels.

[6] As a youth, Joseph and fellow future NBA player Kelly Olynyk were both on a Scarborough Blues club team that rarely lost in the late 1990s and early 2000s.

[5] In 2008, he and Devoe were selected to play in the annual All-Canada Classic, which showcases the top high school players in Canada.

Later that year, at age 16, Joseph transferred to Findlay Prep in Henderson, Nevada with Tristan Thompson, his close friend and AAU teammate.

In August 2009, Joseph was selected to play in the fourth annual Boost Mobile Elite 24 basketball game at Rucker Park in Harlem, New York City.

Joseph played one of his best games on December 18, 2010, recording a season-high 21 points and a game-winning jumper against North Carolina.

Texas lost to fifth-seeded Arizona in the third round with a standout performance and game-winning shot from Derrick Williams.

[17] The 2011 draft was also the first time three Texas Longhorn basketball players went in the first round after Joseph's former collegiate teammate Jordan Hamilton went 26th overall to Dallas Mavericks.

Joseph helped the Spurs reach the 2013 NBA Finals against the Miami Heat, but San Antonio lost the series in seven games.

[25][26] He made his debut for the Raptors in their season opener on October 28, 2015, recording three points and two rebounds in a 106–99 win over the Indiana Pacers.

[28] On November 28, 2015, he scored 12 points and made a three-pointer at the buzzer following a well-worked inbounds play, lifting the Raptors an 84–82 win over the Washington Wizards.

On April 16, 2016, Joseph scored a playoff career-high 18 points in a Game 1 loss to the seventh-seeded Indiana Pacers in the first round.

[37] On January 30, 2020, Joseph scored a season-high 16 points, while also getting two rebounds, seven assists, one steal and one block in an 124–103 victory against the Los Angeles Clippers.

[38] On March 26, 2021, Joseph was traded to the Detroit Pistons, along with two future second-round draft picks, in exchange for Delon Wright.

Joseph joined the Canadian men's national basketball team for stage two of their pre-2011 FIBA Americas Championship training camp in early August.

[47] At the 2013 FIBA Americas Championship, he led the team in scoring with 16.1 points per game,[48] playing alongside his brother, Devoe.