Barcelona were second on the list with a value of $4 billion while Manchester United, who held top spot in each of the last two years, were third with a value of $3.8 billion.
Bayern Munich ($3 billion) and Manchester City ($2.69 billion) rounded out the top five.
The 20 most valuable soccer clubs this year are worth an average of $1.75 billion, up 34% from last year, a jump Forbes attributes to sponsors paying more money to attach themselves to these teams.
"Soccer team values are increasing because companies continue to increase the amount of money they pay teams for shirt and kit rights, and sponsorships," said Michael Ozanian, assistant managing editor at Forbes.
"Soccer is the most popular team sport in the world and soccer players are running billboards for brands."
(Reporting by Frank Pingue in Toronto, editing by Ed Osmond)
