The musician, 49, reached the milestone thanks to business interests in fashion, a sports management company and a $70m (£55.2m) stake in Uber.
He has $310m (£245m) in Armand de Brignac champagne, $100m (£79m) in his own cognac, a joint venture with Bacardi, and a $70m (£55.2m) art collection.
Jay-Z and his wife Beyonce also own equity in the streaming service Tidal, which helps bring in more money.
Forbes suggests his net worth "conservatively totals" about $1bn (£789m).
The total was estimated by adding up his income and then subtracting a "healthy amount to account for a superstar lifestyle".
Outside experts checked the figures to make sure they were "fair and conservative".
Jay'Z's nearest on the list is Diddy, worth about $825m (£651m).
Dr Dre was thought to be the first rapper billionaire when he sold his company Beats to Apple in 2014, but he had to pay such a large sum in taxes, his net worth would have been about $800m (£632m).
Jay-Z, real name Shawn Carter, was born in New York City and rose to fame in 1996, releasing debut album Reasonable Doubt.
He married Beyonce, 37, in 2008 and they have three children.
Jay-Z has 14 number one albums, 22 Grammy awards and toured recently with his wife, playing 48 dates around the world in the On The Run II tour.
© Sky News 2019