The judicial committee found the 38-year-old jockey guilty of intentionally and deliberately restraining Watch Your Man and that he failed to give his horse every opportunity. The charge relating to his ride on Lil Mer was dismissed.
The committee then adjourned the inquiry until yesterday for sentencing.
Walker has ridden 872 winners with 45 at Group or Listed level since he started riding in the 1991-92 season.
His career highlights include Group One victories in the New Zealand Derby with C'est La Guerre, the New Zealand Oaks aboard Legs and the Levin Classic on Porotene Gem.
Walker's father, Jim, was a successful Central Districts-based jockey for many years and enjoyed a high-profile association with the multiple Group One winner Veandercross. NZ Racing Desk