Cromwell was chief minister to King Henry VIII of England from 1532 to 1540.
Rylance, the former artistic director of Shakespeare's Globe in London, is currently rehearsing for the lead role in a new play, "Nice Fish," at the Guthrie Theatre in Minneapolis. He is to return to London in September to direct Vanessa Redgrave and James Earl Jones in "Much Ado About Nothing" at the Old Vic, the BBC said.
"Tinker Tailor Soldier Spy" co-writer Peter Straughan is adapting Mantel's books for a six-part series to run on BBC Two.
No start date for filming has been announced.
The BBC said Mantel will serve as a consultant on the program as she also pens the third installment in her trilogy of historical novels.