He was born on March 21, 1910 in Oakland, California to Joseph Gallo, Sr. He had two brothers: his partner in the wine business, Ernest Gallo; and his youngest brother, Joseph Edward Gallo. Joseph Gallo, Sr. died in a murder-suicide when he shot his wife and then took his own life. Julio grew up near Modesto, California and graduated in 1929 from Modesto High School. He married Aileen (1913–1999) and they had: Robert J. Gallo, and Susan Gallo Coleman.
He died on May 2, 1993 when the vehicle he was driving veered off a dirt road on his ranch near Tracy, California. The cause of death was a cervical spine fracture and partial dislocation caused by the blunt-force trauma of the crash. 
- Gallo Family Vineyards
- Henderson, Bruce, with Ernest and Julio Gallo. Ernest & Julio: Our Story. Times Books, 1994
- Eric Pace (May 4, 1993). "Julio Gallo, 83, Wine Industrialist, Dies". New York Times. Retrieved 2010-07-28.
In 1986, the Gallo winery sued Ernest and Julio Gallo's younger brother, Joseph, who had earlier managed vineyards for his brothers. The suit involved accusations of trademark infringement related to Joseph's opening of a cheese factory near his home in Livingston, Calif., using the family name.