Daniel Cormier Says Final Fight will Be Jon Jones at 205 Pounds

Talk about going out with a bang ... Daniel Cormier tells TMZ Sports his fight plan is to finish his UFC career with one final mega-brawl with Jon Jones!!!

The reigning champ champ (he's got both the heavyweight and light heavyweight title) has already set a ticking clock on his UFC career -- promising to retire for good on his 40th birthday, roughly 6 months from now.

First, Cormier says he wants Brock Lesnar in the heavyweight division ... followed by a light heavyweight fight with Jon Jones.

Dana White recently told us he would love to see Jones vs. Cormier III at heavyweight ... but D.C. says he ain't on board with that. He wants the fight at light heavyweight (205 pounds).

"I want to fight Jones at 205, because that's where he beat me," Cormier said ... "He beat me at 205, I want to beat him where he beat me."

In the meantime, D.C. says he'll most likely relinquish his light heavyweight title while he fights Brock at heavyweight ... clearing the way for Jones to fight Alexander Gustafsson for the LHW title.

After that, it's on ... one last battle for the ages.