Palmer connected with Andrew Caldwell for a 6-yard touchdown and Benson ran 1-yard for a score in the first quarter.
Shayne Graham kicked a 23-yard field goal in the second, sending the Bengals ahead 17-0 at the half.
Benson carried 34 times for 117 yards for Cincinnati (6-2).
Palmer completed 20-of-32 passes for 224 yards.
Ray Rice scored on a 2-yard run for the Ravens (4-4).
Baltimore quarterback Joe Flacco connected on 18-of-32 passes for 195 yards and was intercepted twice.
Bengals wide receiver Chris Henry suffered a broken left forearm in the second quarter and was carried off the field.
Copyright 2009 by United Press International.