Vaca turned pro in 1978 and captured the WBC Welterweight Title by beating Lloyd Honeyghan via 8th round technical decision in 1987, but lost the belt to Honeyghan via 3rd KO in a rematch in 1988. Later that year he took on IBF Welterweight Title holder Simon Brown, but lost the bout via 3rd TKO. Although he never got a shot again at another major title, Vaca was destroyed by a relatively young Roy Jones Jr. in one round, in the Light-Middleweight weight-class in 1992. He continued to fight until 2002, mostly in his native Mexico, and retired after a loss to Marco Antonio Rubio. Vaca finished with a record of 66 wins, 24 losses, 2 draws, with 51 knockouts.