The 32-year-old fell from favourite Merry Poppins at Killarney races on Friday afternoon, being treated on the course being sent to Tralee Hospital.
She was “fully conscious” in the ambulance.
"Rachael Blackmore sustained a fractured ankle and hip injury following her fall in Killarney on Friday evening," the Irish Horseracing Regulatory Board (IHRB) said in a statement.
"She has had surgery overnight and is in good spirits this morning.”
The Irishwoman had already won two races on Friday, which was the final day of the Killarney meet.
Blackmore made Grand National history by becoming the first female jockey to win the race by steering Minella Times across the finishing line at Aintree in April.
In March, she became the first woman to be crowned the leading jockey at Cheltenham Festival.
Additional reporting by Reuters.