Ray Rice ran for 107 yards and scored twice for the Ravens, who bolted to a 14-0 lead in the first quarter and never let up against their bitter rivals.
It was a rematch of a second-round playoff matchup last January, when the Steelers rallied to beat Baltimore 31-24. In that game, the Ravens let a 21-7 halftime lead evaporate with three turnovers in the third quarter.
This time, the Ravens got three takeaways in the third quarter to turn a 21-7 advantage into a rout.
Ngata was the driving force, causing a fumble and deflecting a pass that produced an interception. Pittsburgh's eight-game winning streak in season openers ended.
"That's pretty easy to assess, ladies and gentlement," said Steelers coach Mike Tomlin. "We got handled in all three areas."
Tomlin said the Steelers suffered no major injuries. James Harrison left the game late with a knee contusion, and Tomlin explained that James Farrior was replaced by Larry Foote for an extended stretch of the first half as planned.
"We don't like it, but we accept it," Tomlin said of the loss. "We'll respond accordingly."