The Steelers won their second straight Super Bowl in a row, largely through the plays by Lynn Swann and by stopping a rally by the Cowboys late in the fourth quarter. Officials did not call a single penalty on the Steelers during the game, while the Cowboys were called for only 2 penalties for 20 yards.

On the opening kickoff, the Cowboys ran a reverse where rookie linebacker Thomas "Hollywood" Henderson took a handoff from Preston Pearson and returned the ball a Super Bowl record 48 yards before kicker Roy Gerela forced him out of bounds at the Steelers 44-yard line. But on the first play of the game, Steelers defensive lineman L.C. Greenwood sacked Cowboys quarterback Roger Staubach, forcing him to fumble. Although Dallas recovered the fumble, they eventually were forced to punt. Pittsburgh managed to get one first down an advance to Dallas 40-yard line, but then they too were forced to punt. However, Steelers punter Bobby Walden fumbled the snap. Walden managed to recover his own fumble, but Dallas took over on Steelers 29-yard line. On the very next play, Staubach threw a 29-yard touchdown pass to wide receiver Drew Pearson, taking a 7–0 lead.

Instead of trying to immediately tie the game on a long passing play, the Steelers ran the ball on the first four plays of their ensuing possession, and then quarterback Terry Bradshaw completed a 32-yard pass to wide receiver Lynn Swann to reach the Cowboys 16-yard line. Two running plays further advanced the ball to the 7-yard line. Then on third down and one, the Steelers managed to fool the Cowboys. Pittsburgh brought in two tight ends, which usually signals a running play. After the snap, tight end Randy Grossman faked a block to the inside as if it were a running play, but then ran a pass route into the endzone, and Bradshaw threw the ball to him for a touchdown, tying the game, 7–7.

Dallas responded on their next drive, advancing the ball 51 yards and scoring on kicker Toni Fritsch's 36-yard field goal to take a 10-7 lead early in the second quarter. The Steelers subsequently advanced to the Cowboys 36-yard line on their next possession, but on fourth down and two, Bradshaw's pass was broken up by Dallas safety Cliff Harris.

Later in the period, Dallas drove to the Steelers 20-yard line. But in three plays, the Cowboys lost 25 yards. On first down, fullback Robert Newhouse was tackled for a 3-yard loss by linebacker Andy Russell. Then Greenwood sacked Staubach for a 12-yard loss. And on third down, Staubach was sacked again, this time for a 10 yard loss, by defensive tackle Dwight White. The sacks pushed Dallas out of field goal range and they were forced to punt. The Steelers offense got the ball back their own 6-yard line with 3:47 left in the half. On the drive, Bradshaw completed a 53-yard pass to Swann to advance the ball to the Cowboys 37-yard line; Swann's catch has become one of the most memorable acrobatic catches in Super Bowl history. But the drive stalled at the 19-yard line, and ended with no points after Gerela missed a 36-yard field goal attempt with 22 seconds remaining in the period.

Early in the third quarter, Pittsburgh got a great scoring opportunity when defensive back J. T. Thomas intercepted a pass from Staubach and returned it 35 yards to the Cowboys 25-yard line. But once again the Steelers failed to score as the Dallas defense kept Pittsburgh out of the end zone and Gerela missed his second field goal, a 33-yard attempt. After the miss, Harris mockingly patted Gerela on his helmet and thanked him for "helping Dallas out," but was immediately shoved to the ground by Steeler linebacker Jack Lambert. Lambert could have been ejected from the game for defending his teammate, but the officials decided to allow him to remain.

The third quarter was completely scoreless and the Cowboys maintained their 10-7 lead going into the final period. But early in the fourth quarter, Dallas punter Mitch Hoopes was forced to punt from inside his own goal line. As Hoopes stepped up to make the kick, Steelers running back Reggie Harrison broke through the line and blocked the punt. The ball went through the end zone for a safety, cutting the Dallas lead to 10–9. Then Steelers running back Mike Collier returned the free kick 25 yards to the Cowboys 45-yard line. Dallas halted the ensuing drive at the 20-yard line, but this time Gerela successfully kicked a 36-yard field goal to give Pittsburgh their first lead of the game, 12–10. Then on the first play of the Cowboys' next drive, Steelers defensive back Mike Wagner intercepted a pass from Staubach and returned it 19 yards to the Dallas 7-yard line. The Cowboys defense again managed to prevent a touchdown, but Gerela kicked an 18-yard field goal to increase the Steelers lead to 15–10.

The Steelers regained possession of the ball on their own 30-yard line with 4:25 left in the final period, giving them a chance to either increase their lead or run out the clock to win the game. But after two plays, the Steelers found themselves facing 3rd down and 6 on their own 36-yard line. Assuming that the Cowboys would be expecting a short pass or a run, Bradshaw decided to try a long pass and told Swann in the huddle to run a deep post pattern. As Bradshaw dropped back to pass, Harris and linebacker D.D. Lewis both blitzed in an attempt to sack him. But Bradshaw managed to dodge Lewis and throw the ball just before being leveled by Harris and lineman Larry Cole, who landed a helmet-to-helmet hit on Bradshaw. Lynn Swann then caught the ball at the 5-yard line and ran into the end zone for a 64-yard touchdown completion. Bradshaw never did see Swann's catch or the touchdown since Coles' hit to Bradshaw's helmet knocked him out of the game with a head injury. It was only after he was assisted to the locker room that he was told what happened.

After play resumed, Gerela missed the extra point attempt, but the Steelers now had a 21–10 lead with 3:02 left in the game, and the Cowboys needed two touchdowns to come back.

Staubach then led his team 80 yards in 5 plays on the ensuing drive, scoring on a 34-yard touchdown pass to wide receiver Percy Howard and cutting their deficit to 21–17 (Howard's touchdown reception was the only catch of his NFL career). After Gerry Mullins recovered Dallas' onside kick attempt, the Steelers then tried to run out the clock on the next drive with four straight running plays, but the Cowboys defense stopped them on fourth down at their 39-yard line, giving Dallas one more chance to win. Some questioned why Noll would elect to go for it on fourth down but, as later explained by NFL films, his entire kicking game had been suspect all game long with Gerela missing an extra point and two field goals while Walden fumbled a snap on a punt and nearly had two others blocked. (Gerela's problems may have begun on the opening kickoff when he was forced to make a touchdown saving tackle on Hollywood Henderson.)

With 1:22 left in the game, Staubach started out the drive with an 11-yard scramble to midfield, and then followed it up with a 12-yard completion to Preston Pearson at the Steelers 38-yard line. On the next play, Staubach fumbled the snap but managed to recover the ball and throw it out of bounds. On second down, he threw a pass intended for Howard in the end zone, but the ball bounced off Howard's shoulder, and a Hail Mary replay was not to be. Then on third down, Staubach once again tried to complete a pass to Howard in the end zone, but the ball was tipped by Wagner into the arms of safety Glen Edwards for an interception as time expired, sealing Pittsburgh's victory.

Bradshaw finished the game with 9 out of 19 pass completions for 209 yards and two touchdowns, with no interceptions. He also added another 16 yards rushing the ball. Staubach completed 15 out of 24 passes for 204 yards and two touchdowns with three interceptions. He also rushed for 22 yards on five carries, but was sacked seven times. Steelers running back Franco Harris was the leading rusher of the game with 82 rushing yards, and also caught a pass for 26 yards. Newhouse was the Cowboys top rusher with 56 yards, and caught two passes for 12 yards. Greenwood recorded a Super Bowl record four sacks but it has gone unrecognized since the NFL didn't officially record sacks until 1982.

Super Bowl X Statistics
Scoring summary
DAL - TD: Drew Pearson 29 yard pass from Roger Staubach 7-0 DAL
PIT - TD: Randy Grossman 7 yard pass from Terry Bradshaw 7-7 tie
DAL - FG: Toni Fritsch 36 yards 10-7 DAL
PIT - Safety: Reggie Harrison blocked punt through end zone 10-9 DAL
PIT - FG: Roy Gerela 36 yards 12-10 PIT
PIT - FG: Roy Gerela 18 yards 15-10 PIT
PIT - TD: Lynn Swann 64 yard pass from Terry Bradshaw (kick failed) 21-10 PIT
DAL - TD: Percy Howard 34 yard pass from Roger Staubach 21-17 PIT

Final Score
Pittsburgh Steelers - 21
Dallas Cowboys - 17

Super Bowl X MVP Lynn Swann Pittsburgh Steelers
Steelers receiver Lynn Swann, who caught four passes for a Super Bowl record 161 yards and one touchdown including a diving catch after tripping over Cowboys' cornerback Mark Washington in the second quarter, was named the Super Bowl's Most Valuable Player. Swann was the first wide receiver to win the Super Bowl MVP award.