The game set a new record for the most-watched event in US television, beating last year's audience of 112.2 million.
Viewing peaked at 120.8 million during the last quarter, which saw the New England Patriots beat the Seattle Seahawks 28-24.
Some 118.5 million watched Katy Perry's half-time show - three million more than last year's show with Bruno Mars.
Ratings compiler Nielsen said the 12-minute performance - which also featured Lenny Kravitz and Missy Elliot - attracted the biggest half-time audience since 1991.
NBC, which broadcast the game, said the actual audience was likely to have been higher because official ratings did not count people watching in locations such as sports bars.
An additional 600,000 viewers watched the game with Spanish-language announcers on NBC's Universo cable network.
NBC Sports also offered a live stream to computers and tablets - attracting an average 800,000 people, according to Adobe Analytics.
After the game, an estimated 26.5 million people kept their TVs on NBC to watch an episode of James Spader's crime drama The Blacklist, making it the most-watched scripted programme on the network in more than a decade.
Next year's Super Bowl will be played in Santa Clara, California, and will be broadcast by CBS.
An estimated average of 114.4 million people watched Sunday's Super Bowl on NBC, according to initial figures.