On 2 August 2019, Čančar signed his rookie contract with the Denver Nuggets.[7]
On 13 May 2021, Čančar scored a career-high 14 points off the bench in a 114–103 win over the Minnesota Timberwolves.[8][9]
On 3 January 2022, during a 89–103 loss to the Dallas Mavericks, Čančar suffered a right foot injury. Two days later, he was diagnosed with a fracture of his right fifth metatarsal.[10] On 7 January, Čančar underwent surgery for the fracture and was ruled out for at least three months.[11]
On 10 April, in the regular season finale, Čančar returned to the Nuggets and played a season high 24 minutes in an overtime loss to the Los Angeles Lakers. Čančar recorded 2 points, 8 rebounds, and 4 assists in his last regular season game.[12]
On 7 July 2022, Čančar re-signed with the Nuggets on a three-year deal.[13]
On 23 November 2022, Čančar scored a career high 20 points, along with 4 rebounds, 5 assists and 3 blocks in an overtime win against the Oklahoma City Thunder.[14][15]
In June 2023, Čančar won his first NBA championship when the Nuggets defeated the Miami Heat in the 2023 NBA Finals. In the last season, he played in 60 games, almost 15 minutes per game, and gave approximately five points per match.[16] In the final series of five matches, he played for 29 seconds.[17]
On 9 July 2024, Čančar re-signed with the Nuggets.[18]