The Grammy-winning artist, whose real name is Clifford Harris Jr., was released early in the morning, said Federal Bureau of Prisons spokesman Chris Burke.
T.I.'s manager, Jason Geter, said the rapper is happy to be out.
"He's out, he's good," said Geter, who co-founded Grand Hustle Records with T.I.
A spokesman for T.I. said the newly freed rapper is planning to celebrate his recent birthday and host a private brunch for family and friends Sunday in Atlanta. He is also expected to attend the BET Hip-Hop Awards on Saturday.
The rapper will serve a year of federal probation.
T.I. first served about seven months in prison in 2009 after his arrest on federal gun charges. He was released on probation and then arrested on drug charges in 2010 in Los Angeles. That arrest violated his probation - during which he was ordered not to commit a crime and not to illegally possess any controlled substances - and led to an 11-month prison sentence at an Arkansas prison.
He was transferred to a halfway house Aug. 31 to finish out the last month or so of his sentence, but he was quickly taken back into federal custody. Federal officials were upset T.I. traveled with a TV producer and manager to the halfway house, accusing him of violating prison rules discussing business deals during the 375-mile journey to Atlanta. T.I.'s attorneys fought the move, and he was sent back to the halfway house Sept. 15.
T.I.'s attorney, Steve Sadow, had argued the artist didn't break any rules because a VH1 reality show and book deal that was announced within hours of his release were finalized months earlier.
Sadow declined comment Thursday, saying T.I. is now free to talk to the media on his own.