Real`s arch-rivals Barcelona rose two places to second on the list, pushing Manchester United down to third.
Paris Saint-Germain and Bayern Munich completed the top five.
Manchester City, Arsenal, Chelsea and Liverpool occupied places six to nine, all of them notching up healthy increases in revenues.
Tottenham were in 12th spot, with Newcastle United and Everton at 17th and 18th.
Meanwhile, West Ham was a new entrant at number 20, making the top 20 for the first time since 2005-06.
The list only looks at revenues accrued and does not take into account club debts.
All the 20 clubs represented are from the "big five" European leagues, with Italy contributing four clubs, Germany three, Spain three and France one.
Real Madrid saw revenues of €577m (£439m, at average exchange rate for the year ending 30 June 2015).
The club saw revenue growth of €27.5m, including an increase of €22.7m in commercial revenues from the previous season.
Other findings include:
-Bayern Munich`s fall from third to fifth place left them in their lowest position since 2006-07
-Italy`s AS Roma was a new entrant into the top 20 after its revenues rose more than 40%
-Other Italian clubs had a tougher time, with Inter Milan and AC Milan both slipping two places, although Juventus stayed at number 10
Although Manchester United fell one place, they remain the highest-grossing Premier League club, earning €519.5m (£395.2m).
"Despite a reduction in revenue year-on-year, the fact that Manchester United remain in the top three of the Money League demonstrates the underlying strength of the club`s business model," said Tim Bridge, senior manager at Deloitte.
"The return to Champions League football, as well as the commencement of a number of significant commercial partnerships, will 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, with the club forecasting revenues of around £500m (around €650m)."
Once again, the list was drawn from England`s Premier League, Germany`s Bundesliga, Italy`s Serie A, Spain`s La Liga and France`s Ligue 1.
"The 2014-15 Money League has been another year of growth for the big five European leagues," said Dan Jones, partner in the Sports Business Group at Deloitte.
"However, we have also seen a slowdown of growth from the top five clubs, with revenues growing by just 4% year on year, compared to 11% in the previous edition.
"It may be hard for new clubs to break into the top 10 in the short term, given the €43.3m revenue gap between 10th and 11th place."
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