The El Paso County medical examiner's office released a report Wednesday attributing the actor's death to a cancerous tumor obstructing a large vein.
Hemsley died at his home in El Paso on July 24. He was 74.
The Philadelphia-born Hemsley played George Jefferson in the CBS sitcom "All in the Family," then starred in the spinoff "The Jeffersons" from 1975 to 1985. It was one of TV's longest-running and most successful sitcoms, particularly noteworthy with its mostly black cast.
Hemsley made George Jefferson - the bigoted, blustering Harlem businessman - one of TV's most memorable characters and a symbol for urban upward mobility.