BBC News: David Mullins: Grand National-winning jockey retires from saddle aged 24
He also finished second aboard Pleasant Company two years later.
"When you leave school at 16 you feel trapped into being a jockey. It's relentless. There is no break," he told the Racing Post.
Mullins was 19 and competing in his first Grand National when he rode his 33-1 shot to victory five years ago.
He won on Bellshill and Faugheen for his uncle at the 2018 Punchestown Festival and now hopes to forge a career in bloodstock sales.
Mullins returned to action after a bad fall in October 2019 and rode a total of 211 career winners, with his last ride coming on 13 January when he was third on Blackbow at Naas.
"It just didn't fit with what I wanted to do any more, but racing is a tough game to get out of, and I've been trying for the last year to 18 months," he said.