Thomas entered the game late in the first quarter to a standing ovation from the Denver crowd. He finished with eight points and two assists in 13 minutes in the 120-118 win.
Thomas, who was upgraded to questionable for the game in Denver, made his decision to play on Wednesday morning. He practiced 5-on-5 on Tuesday and participated in a shootaround Wednesday morning.
Thomas, 30, is returning to a Nuggets team (38-18) that is within three games game of first-place Golden State in the West and is employing a bevy of talented guards, including Jamal Murray, Gary Harris, Malik Beasley, Will Barton and Monte Morris.
Thomas averaged 28.9 points per game for the Boston Celtics in 2016-17, a second-team All-NBA season that appeared to be clearing the way for a long-term, $100 million contract.
But an injury to the same right hip cut short his playoffs in 2017 and cost him eight months of rehab. That and a summer trade to the Cleveland Cavaliers upended his hopes for such a lucrative, long-term deal.
Thomas joined the Los Angeles Lakers as part of a trade-deadline deal with Cleveland, where he had played only 15 games in 2017-18.