Involved with horse racing since his teens, Headley worked as an exercise rider from 1949 until taking out his trainers license in 1959. Based in California, he first gained national attention with Bertrando who won the 1991 Norfolk Stakes by a record nine lengths and went on to a second-place finish behind a brilliant performance by European star, Arazi. Headley's greatest success to date came with the Champion sprint horse Kona Gold, a winner of multiple stakes races including the 2000 Breeders' Cup Sprint. In addition to being the horse's trainer, Headley is also a one-third partner.
In 2003, Bruce Headley trained Got Koko, owned by his wife Aase in partnership with Paul Leung. The filly became just the third-ever winner of the La Cañada Series at Santa Anita Park since its inception in 1975. The three-race series consists of the La Brea, El Encino and La Cañada Stakes for newly turning/turned 4-year old fillies run at an increasing distance.