United, the world's wealthiest club, have 73.3 million followers on Facebook, which Arnold said was more than the NBA, MLB, NFL and NHL combined. They also have 18.5 million followers on Twitter.
Some pundits have said that United's focus on the club's commercial interests is a distraction from the need to get back to the top in the Premier League but Arnold said the two go hand-in-hand.
"Commercial success is only possible because of the unparalleled engagement we have with our fans. The end goal is creating a virtuous circle, where more engagement with our fans equals greater opportunities for our partners," he said.
"And that in turn equals greater revenue, and more opportunities for academy investment and world class signings to deliver the performances and success United fans expect and deserve. Expressed simply, for us to win on the pitch, we have to win off it."
United, who have won a record 20 English league titles, have not finished top of the Premier League since 2013 and currently sit in seventh place.
But interest in the club shows no signs of waning and Arnold said United were responsible for generating 44 percent of all Premier League club interactions on Facebook, Twitter and Instagram.
The club have a series of commercial partners including Chevrolet, Adidas, Aon and Aeroflot and their content strategy, includes their own MUTV channel, YouTube channel, club website and print publications.
Arnold said the millennial demographic accounted for 51 percent of United fans and followers as well as 77 percent of their social media following.
The club, listed on the New York Stock Exchange, are controlled by the American Glazer family.
United have forecast revenue for 2018-19 to rise to record levels, between 615 million pounds ($804 million) and 630 million pounds in the year to next June.
(Reporting by Simon Evans, editing by Pritha Sarkar)
