Davy Condon has retired after being advised by a doctor to never ride again because of the risk of causing further damage to his spine.
The Irish jockey fell from Portrait King during the Grand National at Aintree earlier in April.
It left him with spinal concussion for the second time in a year.
"I was hoping that I might still be able to ride out, " Condon, 30, said. "But he told me I can't even exercise horses, that it's too dangerous."
Dr Adrian McGoldrick, senior Turf Club medical officer, said a doctor had recommended that Condon retire.
He added Condon could not ride "professionally or recreationally due to risk of further spinal injury".
It was initially thought Condon had escaped serious injury and suffered concussion in the fall three fences from the finish.
But he has now been referred to a neurosurgeon for an ongoing disc legion in his neck.
Dr McGoldrick said Condon had accepted the decision and would liaise with the Irish Jockeys' Trust about his career options.
Last August the jockey fractured three vertebrae after a fall from Cheltenham Festival winner Flaxen Flare in Cork.
In 2007 he suffered a similar injury in a fall at Punchestown.
Condon's biggest wins were Cheltenham Festival victories on Ebaziyan and Flaxen Flare.
Trainer Gordon Elliott paid tribute to Cordon, posting on Facebook: "Very sad to say that Davy Condon has been forced to retire from racing due to injury.
"Davy has been an integral part of the team and has ridden some of the biggest winners I have had in my short career. Davy will not only be missed by myself, he is a very popular person in the industry and here at Cullentra."
Fellow jockey Robbie McNamara is recovering from spinal surgery after suffering serious injuries in a fall at Wexford on 10 April.