Ronda Rousey's Fighting Amanda Nunes In Dec

SHE'S BACK!!!

Ronda Rousey will finally make her return to the Octagon in December -- when she fights Amanda Nunes for the womens bantamweight title at UFC 207 in Las Vegas.

Dana White just made the announcement on "The Herd" on FS1 -- and says she's good to go on Dec. 30th.

Ronda hasn't fought since losing to Holly Holm at UFC 193 in Nov. 2015.

Dana said Ronda had a "bad loss and lost her title but she's still Ronda Rousey at the end of the day."

Dana says Ronda's in a good place psychologically.

By the way, Nunes called out Rousey back in July -- saying she can't wait to beat Ronda's ass so she can prove to everyone she DESERVES to be the champ.

White says Ronda also wants to fight Cris "Cyborg" at some point down the line -- as he previously told TMZ Sports. But first, she wants to win her title back.