New York - Diddy is said to be working on a long-awaited album but, even without his music, he was the top-earning rapper of the past year.
Releasing its annual list on Tuesday, Forbes said that Diddy - whose real name is Sean Combs and whose stage names include Puff Daddy - took in $60m from June 2014 to June 2015.
His earnings come mostly through his business projects, especially his venture selling French-made Ciroc liquor, the wealth magazine said.
Diddy rarely performs and last released an album, Last Train to Paris, in 2010.
But Gizzle, an artist signed to his label, recently told the Rap-Up website that Diddy was working on a sequel to his debut 1997 work No Way Out.
No Way Out 2 would be the final album from Diddy, Gizzle said.
Another rapper turned mogul, Jay Z, was close behind at number two by raking in an estimated $56m, Forbes said.
Jay Z put on a series of sold-out arena shows with his wife Beyoncé and has earned money through assets such as Armand de Brignac, a champagne that he bought last year.
Canadian rapper and Apple collaborator Drake came in third at $39.5m, with Forbes estimating that he earned $1m per show.
Drake is the only artist to go platinum in the United States, or sell more than one million copies, with an album released this year - the mixtape If You're Reading This It's Too Late.
Drake released a new mixtape, What a Time To Be Alive, with fellow rapper Future late on Sunday, with Billboard magazine expecting the work to top the latest album chart.
In 2013-14, Forbes said that Dr. Dre topped the list - and set the record for an entertainer of any genre in a year - by earning $620m.
Dr. Dre had sold Beats, the company he co-founded that is best-known for headphones, to Apple, where he has taken on a corporate role.
Forbes estimated that he came fourth in 2014-15 with $33m in earnings.
Dr. Dre last month released Compton, which he has described as his final album, to accompany the blockbuster film Straight Outta Compton about his former band N.W.A.