The central character is an orphaned young woman who gets swept up in the lives of the rich.
“The Gilded Age” is a co-production by HBO and Universal Television, which along with NBC is part of media giant NBCUniversal.
HBO was the best fit for the series, Paul Telegdy and George Cheeks, co-chairmen of NBC Entertainment, said in a statement.
“We love the ambition and scope of ‘The Gilded Age,’ and after a highly competitive bidding process, ultimately came to the conclusion that HBO is the perfect network for this epic story,” the executives said.
Casey Bloys, HBO’s programming president, said the series will be opulent in scope and scale and is a “richly textured character drama” that’s right for HBO.
Fellowes, who wrote the upcoming “Downton Abbey” movie, is writing “The Gilded Age” and producing it with Gareth Neame and Michael Engler. Neame was a producer on PBS’ “Downton Abbey” and is a producer on the big-screen version.