Matranga was born in Balestreti, Sicily, he entered the United States illegally in 1925 and became a naturalized U.S. citizen on October 30, 1942 in Florida. He resided and operated in San Diego, California along with his brothers and fellow members of the Los Angeles crime family, Joseph Matranga and "Big Frank" Frank Matranga. Gaspare was also a close associate of Los Angeles hitman and capo Jimmy "the weasel" Fratianno. He was arrested on two separate occasions in 1954 for assault with a deadly weapon. He was the owner of the Cuckoo Club in San Diego and part owner of a record store along with Frank "Bomp" Bompensiero. Matranga was a known professional assassin for the mafia. He was considered the most violent of the Matranga brothers.