Manchester United were valued at $3.69 billion (about £2.86 billion, about N1.476 trillion) and returned to the top of the annual list for the first time in five years.
Real Madrid’s Spanish rivals FC Barcelona were second with a worth of $3.64bn (about £2.82bn), as Real with $3.58bn (£2.77bn) went down to third.
Six English clubs were in the top 10, with Manchester City, Arsenal, Chelsea, Liverpool and Tottenham joining Manchester United.
German champions Bayern Munich were fourth, while Italian title winners Juventus were ninth.
Real Madrid, winners of the Champions League and Spanish title in the past season, had been top for the past four years.
But they saw their value drop by 2 per cent as Manchester United’s went up by 11 per cent.
“Manchester United’s return to the top spot is a testament to their powerful brand and marketing acumen,” Forbes Media assistant managing editor Mike Ozanian said in a statement.
Leicester, who won the English Premier League in 2015-16, were 19th and West Ham 15th.
Forbes’ top 20 most valuable football teams