The "30 Rock" actor will star in the Weinstein Co film, directed by Lee Daniels, reported Variety.
"Mr Foxx, I hope I do you justice!It will be an honour to portray an icon," said Morgan.
Foxx was best known for raunchy comedy "party albums" in the 1950s and 1960s, and starred for six seasons in the sitcom "Sanford and Son" from 1972 to 1977.
Pryor broke into the business in the early 1960s and had become the top stand-up comedian in the business by the early 1970s.
Other cast members in this untitled biopic include, Kate Hudson as Pryor's wife, Taraji P Henson and Murphy as Pryor's parents and Oprah Winfrey as Pryor's grandmother, who raised him.