The new study found that Barca generated a record-breaking revenue of $935.9m (840.8 million euros) last season, becoming only the third club to hold the top position.
As a result, Real Madrid slip into second with $842.9 million whilst Manchester United remained in third.
The report outlines how the Catalan club has reduced its reliance on broadcast revenue deals and shifted its focus on revenue channels within its control.
The Spanish giant is expected to retain its top spot for next year and could become the first $1 billion Money League club in future seasons.
The positions are ranked on clubs’ ability to generate revenue from factors such as matchday sales, broadcast rights, and commercial sources — based on the 2018/19 season. It does not include money generated from player sales.
The top 20 money-spinning clubs generated a staggering $10.3 billion in the 2018-19 season, an 11% increase from the year before.
Elsewhere, Manchester United is at risk of losing its position as the highest-earning English Premier League club next year due to its declining performances on the pitch.
The Old Trafford outfit failed to qualify for the UEFA Champions League this season and currently sit outside the qualification spots for next year’s edition.
Deloitte says the club’s predicted revenue for the current season “would likely see the club fall to its lowest ever Money League position in next year’s edition.”
However, United’s current demise is good news for two of its fiercest rivals.
League champion Manchester City, meanwhile, falls down one place to sixth but is likely to return to the top five next year should its new commercial deals be twinned with a run in this season’s Champions League.
Elsewhere, eighth-placed Tottenham climbed to its highest ever position to become London’s top revenue generating club for the first time since 1996-97.
It leapfrogged above both Chelsea and Arsenal, with the latter falling out of the top 10 due to its continued absence from Europe’s most prestigious tournament.
Regaining its place in the top 10 is Juventus, with the Italian champion having one man in particular to thank.
The arrival of Cristiano Ronaldo in 2018 has allowed the club to capitalize on his image which has seen an 17% increase in revenue.
The talisman has more Instagram followers than Real Madrid and Barcelona combined which, according to Deloitte, has “undoubtedly increased Juventus’ commercial appeal.”
There are only two new teams to break into the top 20 this year with Olympique Lyonnais and Napoli stepping up into 17th and 20th respectively.