The Irish rider, 31, was top jockey at the Cheltenham Festival – where she won the Champion Hurdle – and crowned a fabulous season with an historic triumph in the world’s greatest steeplechase.
The writing was on the wall when she took Minella Times into the lead before the final fence, although she had to keep the Henry de Bromhead-trained eight-year-old up to his work as the famous Elbow approached.
Blackmore and Minella Times (11-1) were not for stopping, though, and galloped into racing folklore to win in the colours of JP McManus.
“I just cannot believe it. He was an absolutely sensational spin," said Blackmore, who is now almost certain to be named as the RTE Sportsperson of 2021.
“What Henry de Bromhead does with these horses, I don’t know! I’m so lucky to be riding them, I just cannot believe I’m after winning the Grand National. This is unbelievable.”
The manner of Blackmore's triumph confirmed her status as the best jockey in the business, as she saluted Minella Times.
“He was just incredible, he jumped beautifully," she added. "I was trying to wait for as long as I could – when we jumped the last and I asked him for a bit, he was there. It’s just incredible.
“I don’t feel male or female right now – I don’t even feel human. This is just unbelievable.”
Balko Des Flos (100-1), ridden by Aidan Coleman, was second to give De Bromhead an incredible one-two in a race when Irish-trained horses took the first five places in the Grand National.
Any Second Now (15-2) was third, with Burrows Saint (9-1) fourth and Farclas (16-1) fifth, as Irish-trained horses filled all those places.
A delighted De Bromhead, who also trained the first two home in last month’s Cheltenham Gold Cup, made clear his admiration for Blackmore.
“She’s brilliant, isn’t she?” he said. “Aren’t we so lucky to have her? They broke the mould after her – she’s brilliant.”
So too was Minella Times, who had six and a half lengths to spare from his stablemate – with another length and three-quarters to Any Second Now and then a long gap to Burrows Saint.
The County Waterford trainer added: “It’s just brilliant. It’s down to Rachael, obviously.
“She was brilliant going into today, I’m delighted … amazing, super ride.
“She hardly left the rail, she was just brilliant on him. It was brilliant to get it for the McManuses.
“I’m over the moon – Balko was super as well. Aidan was super on him, he ran an absolute cracker as well.
“It feels amazing, it really does. It’s incredible, stuff you dream of. I’ve been watching (this race) since I was a kid. It’s amazing. I’m just so lucky.”