Authorities were investigating Sage Stallone's death, but details were not immediately available.
"Sylvester Stallone is devastated and grief-stricken over the sudden loss of his son," publicist Michelle Bega said in a statement. "His compassion and thoughts are with Sage's mother, Sasha."
Los Angeles police said they were dispatched to investigate a death at a home on Mulholland Terrace around 2.15pm on Friday.
Coroner's officials also said they were in the initial investigative stages.
"Sage was a very talented and wonderful young man, his loss will be felt forever," Bega said.George Braunstein, a lawyer who has represented Sage Stallone for 15 years, said a housekeeper found his body on Friday afternoon. Friends and acquaintances had become concerned because they hadn't heard from Stallone in the past day, Braunstein said.
Sage Moonblood Stallone was the oldest of Sylvester Stallone's children and co-starred with his father in two films. He was the first of two sons Stallone had with first wife Sasha Czack.
Sage Stallone made his acting debut in Rocky V (1990) and also appeared with his father in Daylight (1996).