The contest included a thrilling finish, with the New England Patriots staging a comeback to defeat the Atlanta Falcons in the National Football league's first-ever Super Bowl overtime. The Patriots returned from a 25-point deficit and quarterback Tom Brady, 39, won his record fifth championship.
The Falcons were in control for much of the game, with a 28-3 lead midway through the third quarter. Viewership surged as the Patriots' pushed the game into overtime, peaking at 117.7 million from 10 p.m. to 10:15 p.m ET.
Without the Patriots' rally, ratings would've been even worse for Fox, which still posted the least-viewed Super Bowl since 2013, when 108.7 million watched the Baltimore Ravens defeat the San Francisco 49ers.
Lady Gaga's halftime show drew 117.5 million viewers.
Last year's Super Bowl drew a 111.9 million viewers to CBS Corp's (CBS.N) CBS, while the Patriots' previous title game appearance in 2015 helped Comcast Corp's (CMCSA.O) NBC television draw 114.4 million viewers, the most-watched TV broadcast in U.S. history.
Despite the lower viewership, the brief overtime, in which the Patriots scored a touchdown in their first possession, allowed Fox to add four more commercials. It is not clear how many more ad dollars Fox was able to get; the network was charging $5 million for 30-seconds of airtime during the game. Fox brought in an estimated $509.6 million in ad revenue for the broadcast, according to research firm iSpot.TV.
Advertising took up 23 percent of the broadcast, with 51 minutes and 30 seconds of commercials. That made it the second-most ad-cluttered Super Bowl game, according to ad-tracking firm Kantar Media.
The four-year viewership low comes on the heels of a disappointing NFL season that saw ratings decline 9 percent and another 6 percent through the playoffs leading up to the Super Bowl. The NFL's four U.S. TV partners, Fox, NBC, CBS and Walt Disney Co's ESPN, are collectively paying $5.4 billion per year under their current media rights contracts.
Much of the ratings decline during the season was blamed on the contentious U.S. presidential election drawing interest away, as well as the lackluster quality of play early in the season. Prior to the Nov. 8 election, ratings were down 12 percent, but were only off by 5 percent after, according to analysis by MoffettNathanson.