The 36-year-old steered 33/1 shot Thanks Be — a three-year-old daughter of Mukhadram who is owned by Emma Capon — to victory in the Sandringham Stakes for trainer Charlie Fellowes.
It has been 32 years since Gay Kelleway became the first lady rider to win on the hallowed turf at the Royal meeting in Berkshire aboard Sprowston Boy.
Hayley announced her retirement from the saddle on 31 August 2015 before making her comeback in 2018. During her spell in retirement she joined the ITV Racing team on television.
After her win today, Hayley revealed she had phoned up the winning trainer to ask whether she could come and ride out at his yard.
“Charlie was quite confident [about the horse’s chances], he said everything was A1, including the ground and the trip. He said the only negative was the draw,” explained a delighted Hayley on ITV Racing.
“Thanks Be just sliced through the field easily. When a gap half comes and you’re going well, it makes it easier to take them. Only having eight stone on her back helped too.
“The standard [of female jockeys] is so high now and they all deserve to be here riding at Royal Ascot. The number of girls riding winners is rising and will only snowball.”
The winning pair beat the William Haggas-trained Magnetic Charm, who is owned by The Queen, by a neck.
The interesting Royal Ascot facts you may not know about...
If you want to keep up with the latest from the equestrian world without leaving home, grab a H&H subscription
The top jockey picked up an impressive four-timer at the Royal meeting yesterday (20 June)
Hayley was awarded an OBE in 2016 for her services to horse racing. She became the first female to ride 100 Flat winners in a year in 2008.
Don’t miss our full report from Royal Ascot in 27 June issue of Horse & Hound magazine.
For all the latest news analysis, competition reports, interviews, features and much more, don’t miss Horse & Hound magazine, on sale every Thursday.