The study was the largest football fan survey ever carried out, with 54,000 respondents from 39 countries taking part.
According to Kantar's findings, the Red Devils have 71m fans in North and South America, 90m in Europe, 173m across Africa and the Middle East, and critically, 325m fans in the ever-expanding Asian market.
A similar study was commissioned in 2007 and, at that time, United only boasted half of their current number of fans.
The clubs's commercial director, Richard Arnold, was understandably pleased by the survey's findings, which added to Forbes magazine's recent declaration that United are the world's most valuable sports brand.
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"Manchester United resonates with followers all over the world, and it’s their passion and support that means year after year we can continue doing what matters most to everyone at the club: playing attacking football and competing for trophies.
"The growth in our followers since 2007 correlates with what we have seen as we have rolled out our new approach to reaching fans.
"From the increase in TV viewership from two to four billion last season, to the demand from millions of media subscribers in 72 countries through our media partnerships, to the way the footage of Wayne [Rooney]'s overhead kick echoed around the world on social media, we can see that the connections to the club are growing exponentially.
"With the DHL Champ19ns Trophy tour we have seen that passion from our community of followers face to face in 38 cities across the globe, and there does not seem to be a beach or street in the world where you do not see the Aon and Nike shirt.
"This survey shows that our family of followers is going from strength to strength."
Kantar's survey also concluded that football is the world's most popular sport with 1.6bn followers worldwide, which is a figure that matches closely with Fifa's recent findings on the game's popularity.