"His career has gone from strength to strength and shows no sign of slowing down."
Corden's first claim to fame came from writing and starring in BBC sitcom Gavin & Stacey.
After being offered $7m a year to present chat show The Late Late Show, he made the move to the US. His Carpool Karaoke segment has proved a global hit, featuring showbiz superstars from Adele to Sir Paul McCartney.
He's now living in an LA mansion worth millions with his wife Julia and their three children.
Fulwell 73 also produces content for Robbie Williams, One Direction, Justin Bieber and Jack Whitehall.
"James has invested wisely in Fulwell, which is a company he cares deeply about. He and the other partners have developed it and made it blossom and it is in a very healthy financial state," the source said.
"It has a lot of overheads and his share isn't cash in the bank but there is no doubt it has been a good investment."
Corden, who was made an OBE in 2015, was praised for paying his Late Late Show team's wages out of his own pocket after Covid-19 affected filming.
It's said he's about to start negotiating a new contract.