The audience was 5 percent bigger than the 86.1 million people who watched the New England Patriots beat the Philadelphia Eagles last year, according to preliminary estimates from Nielsen Media Research.
When the Dallas Cowboys beat the Steelers in 1996, there were 94.1 million people watching.
Super Bowl viewers feasted on another halftime show controversy, when the NFL briefly shut off Mick Jagger's microphone to avoid sexually-suggestive lyrics in two Rolling Stones songs. ABC also scored solid ratings for an episode of "Grey's Anatomy" following the game.
The Steelers beat the Seahawks 21-10, but the game wasn't really decided until the final five minutes or so, which kept the audience glued to the set, said Larry Hyams, ABC research executive.
"The Super Bowl obviously is a national event and people are going to tune in regardless of whether the teams have national appeal," Hyams said. "It's up to the game to hold the audience."
The Super Bowl is traditionally the biggest television event of the year. The Academy Awards, jokingly called the Super Bowl for women, often comes in second; last year, 41.5 million people saw the Oscars.
Pittsburgh had the largest Super Bowl rating (percentage of all sets, whether on or off) of any media market, with a 57.1, Nielsen said. Seattle followed directly behind with a 55.
A total of 141.4 million people watched at least some part of the game, Nielsen said. The 90.7 million figured represented the game's average audience at any given moment.
The "Grey's Anatomy" episode after the game was seen by 38.1 million people, Nielsen said. That's 15 million more than has ever watched a single episode of the medical soap. It was the most-watched entertainment program of the season so far — even beating "American Idol."
Since 1991, only two post-Super Bowl programs have drawn a bigger audience: "Survivor" in 2001 and "Friends" in 1996. It was solid exposure for a series that has already been growing in appeal during its second season.
At halftime, Jagger was silenced during portions of the songs "Start Me Up" and "Rough Justice." An NFL spokesman said the band knew ahead of time that the league — still skittish over Janet Jackson's wardrobe malfunction from two years ago — wouldn't accept the particular lyrics.
"It wasn't that big of an issue for us," said Frank Supovitz, the NFL's senior vice president, who said the league wanted to make the halftime show family entertainment.
By David Bauder