He played college basketball for the Georgetown Hoyas and was selected with the third overall pick in the 2013 NBA draft by the Washington Wizards.

Porter attended Scott County Central High School, whose district includes the small communities of Morley, Vanduser, Haywood City, and parts of rural Sikeston.

He earned all-state honors as a junior and senior, leading the Braves to three straight Class 1 state championships and giving Scott Central its state-record 15th title overall.

[2] He signed a letter of intent with the Georgetown Hoyas and played his first game with them on November 12, 2011, against Savannah State, recording 9 points, 8 rebounds and 3 blocks.

At the conclusion of the 2012–13 season, Porter led his team to a 25–7 record and a number 2 seed in the NCAA Division I men's basketball tournament.

For his efforts, he was named the Big East Player of the Year and was a finalist for both the Naismith Trophy and Wooden Award.

[4] On April 15, 2013, Porter announced his decision to forgo his final two years of eligibility and enter the NBA draft.

[18] On July 13, the Wizards announced that the team had retained its right of first refusal and matched the offer sheet extended to Porter by the Nets.

[23] He came off the bench in 13 straight games upon returning, before starting on January 30 against the Indiana Pacers and injuring his left big toe.

[24] On February 6, 2019, Porter was traded to the Chicago Bulls in exchange for Jabari Parker, Bobby Portis and a protected 2023 second-round draft pick.

[27] On March 25, 2021, Porter and Wendell Carter Jr. were traded to the Orlando Magic in exchange for Nikola Vučević and Al-Farouq Aminu.

[32] On February 8, 2024, Porter was traded to the Utah Jazz alongside Kira Lewis Jr. and a 2024 first-round draft pick in exchange for Kelly Olynyk and Ochai Agbaji.

His cousins Corey and Reece Porter[39][40] helped Sikeston High School win its first state title in its first undefeated season.