Between 1942 and 1956, he rode more than 1,000 winners at tracks in Maryland, West Virginia, and New Jersey but constant weight problems eventually forced him to give up riding and turn to training.
John Tammaro along with King T. Leatherbury, Richard E. Dutrow, Sr. and Hall of Fame inductee Bud Delp became known as Maryland racing's "Big Four".
Kinghaven Farms had winter facilities in Ocala, Florida and when Tammaro left their employ in 1985, the then sixty-year-old went to live and work in the Miami area.
In his career, Tammaro won more than 40 stakes races and in 1998 trained Aly's Alley to a second-place finish in the 1998 Breeders' Cup Juvenile.
Son, Michael Tammaro also trained at Woodbine Racetrack where he won the 1986 Queen's Plate with Golden Choice.