The returner/wide receiver, who's spent the past two seasons on injured reserve, agreed to terms on a one-year contract.
"I am truly excited and thankful to say that I will be back in TwoTone Blue next year in TitanNation!" Mariani posted on Twitter. "Can't wait to get back and get started!"
He'll be sure to face stiff competition to win the returner job, as the Titans have both Dexter McCluster and Leon Washington under contract as well.
Mariani played in 32 games during his first two seasons in the NFL with the Titans, earningPro Bowl honors as a kick returner as a rookie in 2010.
For his career, he has three return touchdowns (two punts, one kickoff) and registered an 11.2-yard punt return average and a 24.8-yard kickoff return average.
A seventh-round pick out of Montana in 2010, Mariani also posted five career receptions for 24 yards.
Reach John Glennon at 615-259-8262 or on Twitter @glennonsports.