Roethlisberger completed 21-of-29 passes for 234 yards. He threw two 3-yard touchdown passes to Hines Ward and a 25-yarder to Mike Wallace, all in the second half.
Tyrone Carter scored the Steelers' other touchdown with a 48-yard interception return.
Pittsburgh running back Rashard Mendenhall amassed 155 yards on 22 carries and the Steelers' defense picked off three Kyle Orton passes.
Robert Ayers scooped up a fumble and ran 54 yards for a touchdown and Matt Prater kicked a 40-yard field goal for the Broncos.
Orton was 23-of-38 passing for 221 yards.
Both teams are 6-2.
Copyright 2009 by United Press International.