[1] He began his professional career in the 2007–08 season with the Arkadia Traiskirchen Lions of the Austrian League, averaging 8.5 points in 26 games.

On 22 July 2013, Bjelica signed a three-year deal with the Turkish team Fenerbahçe Ülker, which was led by one of Europe's great coaches, Željko Obradović.

[16] He made his debut for the Timberwolves in their season opener on 28 October 2015, recording eight points and five rebounds in a 112–111 win over the Los Angeles Lakers.

[18] On 13 November 2016, Bjelica made his first career start and scored a career-high 24 points in a 125–99 win over the Los Angeles Lakers.

[23] On 21 July 2018, just days after backing out of a deal with the Philadelphia 76ers with the intention of returning to Europe, Bjelica signed a three-year, $20.5 million contract with the Sacramento Kings.

[28] He made his debut for the Warriors in their season opener on 19 October 2021, recording a double-double off the bench with 15 points and 11 rebounds in a 121–114 win over the Los Angeles Lakers.

[29][30] He became the first player to post a double-double off the bench in his Warriors debut since Sam Williams (16 points, 12 rebounds) on 30 October 1981 at Denver.

[32] He became the fourth NBA player from Serbia who won the championship, joining Darko Miličić, Peja Stojaković, and Ognjen Kuzmić.

[33] On 9 August 2022, Bjelica signed a two-year deal to return to Fenerbahçe Beko, where he was named the EuroLeague MVP of the 2014-15 season.

[36] On 9 October 2023, it was announced that Bjelica has allegedly parted ways with his home town team, after getting caught in a fight with Crvena zvezda head coach Duško Ivanović.

[38] Bjelica played with the senior Serbian national basketball team that won the silver medal at the EuroBasket 2009.

He was also a member of the Serbian national team at the 2010 FIBA World Championship, where Serbia was defeated 99–88 by Lithuania in the game for the bronze medal, after they had earlier lost to hosts, Turkey, in a highly controversial semifinals finish.

During EuroBasket 2013 in Slovenia, Bjelica became one of the veterans of a very young and incomplete Serbia squad, leading the team alongside captain Nenad Krstić and Nemanja Nedović.

Serbia was eventually swept by Spain in the quarterfinals, but the team showed some good performances, particularly against Lithuania and France.

Although his three-point shooting form wasn't impressive during the tournament, he was still one of the most important players of the team, filling all sorts of roles with his handling, passing, rebounding, and scoring.

[42] At the 2019 FIBA Basketball World Cup, the national team of Serbia was dubbed as favorite to win the trophy,[43] but was eventually upset in the quarterfinals by Argentina.

[45][46] Bjelica's statistics suggest he was the third-best player on the team behind Bogdanović and Jokić, averaging 10.7 points, 4.7 rebounds and 2.7 assists over 7 games, while shooting 42.9% from the field.