Real topped the list published on Thursday, with an annual revenue of 577 million euros (443 million pounds) as the combined figure for the top 20 Money League clubs rose by eight percent to a record high of 6.6 billion euros.
Barcelona's stunning success on the pitch in 2015, when they claimed five of the six trophies on offer, including La Liga and the Champions League, helped them move above Manchester United, who fell to third.
It was the first time that the top three clubs in the Football Money League have all passed the 500 million euros revenue mark.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
Spanish giants Real, who clinched a record-extending 10th European Cup in 2014, were buoyed by an increase in commercial revenues which rose by 22.7 million euros from the previous season.
Although Manchester United slipped down the table, the outlook for the record Premier League winners remains positive.
Tim Bridge, Senior Manager at Deloitte, said their return to Champions League football this season as well as a number of commercial partnerships would only strengthen the business in 2015-16.
"With this in mind, it would not be surprising to see United top next year’s Money League for the first time in 12 years," he said in a statement.
Premier League clubs remained the major force in the Money League, nine English teams making the top 20 with revenues totalling 3 billion euros.
Chelsea fell one place to eighth while London rivals Arsenal, who currently top the Premier League, climbed to seventh.
Manchester City and Liverpool were the other two Premier League clubs in the top 10, in sixth and ninth places respectively.
"With the new round of Premier League broadcast deals set to deliver greatly improved domestic broadcast revenues in 2016-17, we expect to see Premier League clubs cementing their places in the top 30 in the coming years, with potential for some of these to climb into the top 20,” Bridge said.
Bayern Munich fell from third to fifth place, their lowest position since 2006-07 and were overtaken by Paris St Germain, the only French team in the top 20.
($1 = 0.9169 euros)
(Reporting by Toby Davis; editing by Ed Osmond)
