It marked the sixth game-winning drive of Flacco's career. The victory gave the Ravens a share of first place in the AFC North.
The drive came minutes after the Ravens were unable to finish off one late in the fourth quarter.
Late in the fourth quarter, Flacco drove the Ravens quickly in the red zone with completions of 21 yards to Houshmandzadeh, 11 yards to Anquan Boldin, 10 yards to Derrick Mason and 11 yards to Todd Heap.
On first and goal, Flacco threw an incompletion to Boldin. On second and goal, Ray Rice's 6-yard run got the Ravens to the Pittsburgh 2-yard line. On third-and-goal, Flacco's pass to Mason was broken up by William Gay. And then Flacco's last pass -- which was a fade route to Boldin in the left side of the end zone -- was so short that it hit the back of Gay's helmet.
The Ravens' third road trip in the first four weeks of the regular season started with some adversity.
After Billy Cundiff was wide right on a 46-yard field goal, the Pittsburgh Steelers delivered their biggest first-half hit to the Ravens' defense. On third-and-3, Batch threw a 34-yard pass to Antwaan Randle El to the Ravens' 1-yard line.
Two plays later, Rashard Mendenhall's 1-yard run handed Pittsburgh a 7-0 lead.
But the Ravens offense immediately responded with an eight-play, 83-yard drive. It began with a 40-yard pass from Flacco to Mason. It ended with a 9-yard run by Willis McGahee, who ran into the end zone standing up to tie the game at 7 in the second quarter.
The Ravens were faced with another tough situation early in the third quarter. McGahee fumbled on the Ravens' first series of the second half, giving the ball to the Steelers at the Ravens' 27-yard line.
Like it did for most of the game, the Ravens' defense stopped Pittsburgh. Terrell Suggs' sack of Batch on third down forced a long field goal. And Jeff Reed's 49-yard field goal ricocheted off right upright, which kept the Ravens' 10-7 advantage intact.
Two series later, Flacco threw a high, haphazard pass to Mason on the left side, where it was intercepted by Pittsburgh cornerback Ike Taylor. Once again, the Ravens' defense didn't budge, giving up a 1-yard run and forcing two incompletions. And once again, Reed missed a long field goal, hooking a 45-yarder wide left into the open end of Heinz Field.
The Ravens' defense finally broke in the fourth quarter. Batch drove the Steelers 93 yards on 13 plays, converting two third downs on the length-of-the-field series.
He hit tight end Heath Miller for a 13-yard pass on third-and-5 and found Randle El for a 16-yard connection on third-and-10.