The Titans announced the deal Monday.
"Ropati gives us the big body we were looking for at the defensive end position. He has played a number of games and been productive," Titans general manager Ruston Webster said in a statement. "He should be an asset for us in the run game at end and also could give us flexibility on game days with the ability to kick inside for some snaps."
Pitoitua is a four-year veteran with 37 games played in stops with the New York Jets and Kansas City Chiefs. He started 10 of his 15 games last year with the Chiefs where he led the linemen with 32 tackles. He also had two sacks, five tackles for loss and a forced fumble.
The Titans also signed defensive tackle Sammie Hill at the start of free agency.