League sources confirmed the signing to BSN Denver.
Childress, 34, hasn't played in the NBA since the 2012-13 season when he appeared in four games for the New Orleans Pelicans. The 6-foot-8 forward played last season with SAN-EN NeoPhoenix of the Japanese League and averaged 18.8 points and 9.5 rebounds per game.
Childress was drafted No. 6 overall by the Atlanta Hawks in 2004 out of Stanford, played four seasons for the franchise and emerged as one of the league's most promising young players, averaging 13.0 points and 6.2 rebounds per game in 2007. He then signed a three-year, $20 million deal with Olympiakos in Greece and returned to the NBA prior to the 2010-11 season with the Phoenix Suns.
The Harbor City, California native is the first player who played in The BIG3 this summer to sign a contract with an NBA team.
In Childress, the Nuggets will bring to training camp a rangy and versatile forward, who can defend multiple positions. Childress was never known for his three-point shot but converted 46 percent of his threes for the Sydney Kings of the NBL during the 2015-16 season. He only shot 33.3 percent from distance last year.
Joe Connelly, one of president of basketball operations Tim Connelly's brothers, coached Childress in Australia and was with the Washington Wizards organization when Childress broke camp with the team in 2014. Connelly was also director of basketball operations for the BIG3 this summer, where Childress played.
With restricted free agent Mason Plumlee still unsigned, the Nuggets have one open roster spot. In total, Denver has 16 players under contract including two-way players Monte Morris and Torrey Craig.