Staged on May 27, Manchester United's game against Barcelona pulled in an audience of 109m, growing to 206m when factoring in people who watched just part of the coverage.
In comparison, the Super Bowl on February 1 between the Pittsburgh Steelers and the Arizona Cardinals attracted 106m, while its total audience standing at 162m.
In third place on the most-watched list was the Abu Dhabi Grand Prix, which closed the Formula 1 season with an audience of 54m.
The men's 100 meters final at the athletics world championships, which saw a world record set by Jamaican Usain Bolt, came in fourth with 33m.
The figures, revealed in a report by London-based agency Initiative Futures Sports and Entertainment, show the ratings power of sporting events in a year without a World Cup or Olympic Games.
While acknowledging that both the Champions League and NFL continue to grow in popularity, the report said that the former is showing more energy for expansion.
The ability of UEFA's showpiece final to open up the Asian market was noted as the main differentiating factor between the two events.
The report's director Kevin Alavay said: "The Champions League has been better able to exploit the large burgeoning populations of the Asia-Pacific region.
"While the Super Bowl has secured free-to-air broadcasting deals in a number of important European markets such as the UK, France and Germany, its distribution and popularity in the key Asia-Pacific region lags far behind the Champions League."