He played college basketball for the San Diego State Aztecs, where he twice earned All-Mountain West Conference (MWC) second-team honors.

He transferred to San Diego City College and averaged 21.1 points, 12.9 rebounds and 3.9 blocks and was named California Community College Athletic Association (CCCAA) co-Most Valuable Player (MVP) and the Pacific Coast Conference Player of the Year.

In his senior year, he was named 2011 All-MWC defensive team after finishing second in the conference in rebounding and blocked shots.

During the NBA lockout that summer, he signed a $350,000 contract to play a season for Mobis Phoebus in the Korean Basketball League.

[14] On January 11, 2012, Thomas was then signed by the San Antonio Spurs, where he was reunited with former Aztec teammate Kawhi Leonard.

[15] He played in his first NBA game on January 13 against the Portland Trail Blazers, getting one rebound in two minutes of garbage time.

[20] On October 3, 2012, Thomas signed a one-year contract with EuroLeague club Maccabi Tel Aviv of Israel.

[33] On December 3, 2013, Thomas signed with the San Antonio Spurs[34] and was assigned multiple time to the Austin Toros.

[38] On July 22, 2014, Thomas was traded by Utah, along with John Lucas III and Erik Murphy, to the Cleveland Cavaliers in exchange for Carrick Felix, a 2015 second round draft pick, and cash considerations.

[47] On October 31, 2015, Thomas was acquired by the Los Angeles D-Fenders, returning to the franchise for a fourth stint.

[51] On July 20, 2017, Thomas signed a two-year deal with Russian club Khimki of the VTB United League and the EuroLeague.

[55] On July 28, 2020, he signed a one-year deal with Bayern Munich of the Basketball Bundesliga (BBL) with the option for another season.

On November 17, 2021, he has signed 1,5 month contract with Petkim Spor of the Turkish Basketball Super League (BSL) with an option to extend until end of season.

[59] In the summer of 2017, Thomas played in The Basketball Tournament on ESPN for team A Few Good Men (Gonzaga Alumni).