He began racing thoroughbreds professionally in 1928 in
Vancouver,
British Columbia. He also raced in
Tijuana,
Mexico before going to
Arcadia, California, where he made his permanent home. Using
Santa Anita Park as his home base, Woolf became one of the premier jockeys of his era; he was known by fellow jockeys and fans as "The Iceman". He earned the nickname for displaying the patience in waiting for the right time to have his horse make a move in a race, as well as his calm attitude before major races, when he could take a nap while other jockeys nervously paced about. While establishing himself as one of America's leading jockeys, he was diagnosed with what is now known as
type 1 diabetes. Only a few years earlier, before the discovery of
insulin, such a diagnosis would have been fatal. Because of his condition, and the nature of diabetes management in the 1930s and 1940s, Woolf had to regulate his weight to avoid rapid
dieting. His racing success allowed him to accept only a few mounts each week, riding only 150–200 races each year compared to as many as a thousand rides other jockeys might undertake, and for years he maintained top physical condition. Despite his limited number of races and a relatively short career, Woolf won ninety-seven major
stakes races around the United States, including the
Hollywood Gold Cup Stakes, the
American Derby and the
Belmont Futurity Stakes three years running. He made history in 1935 when he rode Azucar to victory in the first $100,000 horse race, the
Santa Anita Handicap, defeating such greats as
Equipoise and
Twenty Grand. Woolf finished second twice at the
Kentucky Derby and won the 1936
Preakness Stakes. He is remembered for his tactical performance in the 1938
match race when he rode
Seabiscuit to victory over the heavily favored
U.S. Triple Crown champion,
War Admiral, in the
Pimlico Special at Baltimore, based on advice from his friend, Seabiscuit's injured regular jockey
Red Pollard. When asked which was the best racehorse he had ever ridden, Woolf answered immediately, "Seabiscuit". ==Death==