Locker -- out the lineup since a separated left shoulder in Week 4 -- took advantage of four Dolphins turnovers in throwing for 122 yards with a pair of touchdowns on 9-of-21 efficiency.
Chris Johnson compiled 126 rushing yards with a touchdown while Jared Cook and Kendall Wright each caught a scoring pass for the Titans (4-6), who rebounded from last week's embarrassing loss to the Chicago Bears.
Team owner Bud Adams excoriated the Titans' performance last week, saying he was "at a loss" to explain it.
Ryan Tannehill went 23-of-39 through the air for 217 yards with three interceptions before being benched as the Dolphins (4-5) dropped their second straight.
Reggie Bush also spent time on the sidelines after managing just 21 rushing yards with a first-quarter fumble for Miami.