UFC Star Tommy McMillen Rushed to Hospital After Suspected Overdose

11:34 AM PT -- Tommy McMillen's trainer says he is completely okay and was at his workout yesterday.

Tommy McMillen -- the featherweight UFC fighter sporting a perfect 12-0 record -- was rushed to the hospital on Sunday after cops administered Narcan ... TMZ has learned.

A spokesperson for the Scottsdale Police Department tells TMZ ... McMillen was transported to a hospital after he was found unresponsive in Cake -- a nightclub in the city's Old Town district.

We're told responding officers removed him from the bathroom, then administered Narcan after they said they saw a white, powdery substance on the ground near him.

They then took the unresponsive McMillen to the hospital. He was in stable condition, and it does not appear there were any life-threatening complications when the police checked him into the hospital.

Tommy -- a 28-year-old who fights out of Glendale, AZ -- started fighting professionally in 2019 and has racked up 12 consecutive victories.

He made his UFC debut earlier this year ... and defeated Marwan Rahiki by unanimous decision back in September.

Tommy broke into the UFC after earning a contract by winning a split decision on Dana White’s Contender Series.