Lil Wayne is headed to the big house.

The troubled rapper pleaded guilty to felony gun possession charges Thursday, agreeing to spend a year behind bars.

Wayne, whose real name is Dwayne Carter, 27, was hit with a slew of charges after a loaded 9-mm. gun was discovered in his tour bus two years ago.

He pleaded guilty to attempted possession of a weapon in the second degree, sparing him a possible 3 1/2-to-7-year prison sentence.

The surprise plea came in the middle of what was expected to be a lengthy pre-trial hearing.

"Yes, sir," Carter, wearing black jeans and a white T-shirt under a blue, fur-lined coat, said when asked if he was ready to plea.

Manhattan Supreme Court Justice Charles Solomon called it "a greatly reduced sentence."

Carter, who is out on bail, will be sentenced in February.