Pitoitua, 29, was scheduled to become an unrestricted free agent Tuesday.
In his first season in Tennessee, Pitoitua set career highs in starts (13), tackles (91) and sacks (four).
"Ropati came in last year and filled an important role for us," Titans general manager Ruston Webster said. "He has been productive and with the new coaching staff, we see him filling that same role for us moving forward. His size and length are qualities that benefit our defense and we are happy to have him back."