Ensa Cosby died in Massachusetts from renal disease, according to Andrew Wyatt.
Mr Wyatt provided no other details on the cause of death.
In a statement, Mr Wyatt asked for prayers for the Cosby family and that the family be given peace at this time.
Ms Cosby had been a staunch supporter of her father, standing up for him amid sexual assault allegations.
Last year, she and her two sisters said they believed their father had become a target because of his race.
Cosby lost another child in 1997 when his son Ennis was shot dead during a robbery attempt in Los Angeles.
Ensa Cosby appeared on one episode of The Cosby Show, which ran from 1984 to 1992.