Earlier this week, Racing Victoria stewards sought a lengthy ban after concluding their show cause notice hearing, where the Melbourne Cup winner decided not to challenge the charges issued against him.
On Wednesday morning, the Racing Appeals and Disciplinary (RAD) Board found Weir guilty of three charges of possessing an electric or electronic apparatus capable of affecting the performance of a horse, and one charge of conduct prejudicial to the image, interests or welfare of racing.
The disqualification will come into effect immediately.
Jamie Stier, Racing Victoria's executive general manager of integrity, said: "Mr Weir will not be permitted to participate in the racing industry in any way over the four-year period, including, but not limited to, his participation in the training of horses, attending race meetings and licensed premises and deriving any benefit from the industry.
"In the interests of Mr Weir's owners and staff and the welfare of horses, the stewards have granted permission for licensed trainer Michael Leonard to assume care of Mr Weir's horses for a period of up to 28 days whilst discussions continue for a permanent solution.
"During this 28-day period, Mr Leonard will be permitted to oversee the training of horses at Forest Lodge Stables, however he will not be permitted to nominate horses transferred to him from Mr Weir for any race or official trial.
"Given the size of Mr Weir's stables, the stewards have also granted an extended period of 10 business days for Mr Weir to coordinate the transfer of horses from his care."
Four devices, known as "jiggers", were discovered during a police search on two properties last week.
Weir is one of Australia's most successful trainers and sent out the 2015 Melbourne Cup winner Prince of Penzance, who was famously partnered by Michelle Payne, the first woman to win the coveted prize.
Fellow trainer Jarrod McLean is to fight a similar case, while a charge of failing to assist stewards laid against a third man, Tyson Kermon, is not being pursued.
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