Roethlisberger, who completed a four-game suspension in the wake of sexual misconduct allegations, went 16-of-27 passing for 257 yards.
Five of his completions went to Hines Ward, who gained 54 yards and scored a touchdown for the Steelers (4-1), extending his consecutive games streak with a reception to 183.
The Browns (1-5) turned to rookie signal-caller Colt McCoy, who made his first NFL start. The former Texas Longhorns star connected on 23-of-33 throws for 281 yards with one score and was intercepted twice.
Cleveland's Peyton Hillis gained 41 rushing yards and collected six passes for 49 yards.