He had three children with his third wife, Isabelle, named Isabelle, Elizabeth, and William Farnum Jr. Farnum died from uremia and cancer on June 5, 1953 at Cedars of Lebanon Hospital.
Dia memiliki tiga anak dengan istri ketiganya, Isabelle, bernama Isabelle, Elizabeth dan William Farnum Jr. Farnum meninggal karena uremia dan kanker pada 5 Juni 1953 di Cedars of Lebanon Hospital.