The Bengals had forced overtime when A.J. Green hauled in a desperation, fourth-down pass from Andy Dalton after Baltimore's James Ihedigbo deflected it into his hands.
But the Ravens (4-5) responded in overtime, stopping the Bengals' opening drive before Tucker connected for his game-winning kick.
Joe Flacco made good on 20-of-36 pass attempts with two touchdowns as Baltimore pulled to within 1 1/2 games of Cincinnati for the divisional lead.
Dalton completed 24-of-51 passes for 274 yards with two TDs but was intercepted three times -- including two by Ihedigbo -- as the Bengals (6-4) dropped a second straight.
Green racked up 151 yards on eight receptions.
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