The UFC superstar just got his license to fight in California reinstated -- essentially clearing the way for him to fight at UFC 232 on Dec. 29.

TMZ Sports broke the story ... Jones tested positive for the banned substance Turinabol (an anabolic steroid) before his fight with Daniel Cormier at the Honda Center in Anaheim in July 2017.

The U.S. Anti-Doping Agency meted out a 15-month suspension for Jones -- and the California State Athletic Commission said it would honor that punishment.

Even though Jon's upcoming fight against Alexander Gustafsson is set to go down in Vegas, the Nevada State Athletic Commission won't license him unless he's clear in California.

The good news for Jon ... he appeared at a CSAC hearing on Tuesday with his attorney and the board voted 6-0 to reinstate him and granted him a temporary license.

Jones also paid his $205,000 fine.

After he was reinstated, Jon had a message to the California State Athletic Commission -- "Make sure you guys watch."

For his part, Jones has always insisted he never intentionally took the Turinabol -- claiming he's not a cheater.

At the hearing, CSAC executive director Andy Foster actually defended Jones -- saying, "I do not think Mr. Jones is intentionally a doper."

He added, "I just don’t believe it. If he is, he’s the worst doper in combat sports. He fails the one test he knows is coming."