Hall, who had never previously tasted victory on the Ladies European Tour or LPGA Tour, carded six birdies in a closing 67 to finish on 17 under par, two shots ahead of Thailand’s Pornanong Phatlum.
The 22-year-old, from Bournemouth, is just the fifth British winner of a major and only the third home winner of this event since it achieved that status in 2001, following in the footsteps of Karen Stupples (2004) and Catriona Matthew (2009).
Fittingly she did so with her father Wayne acting as her caddie, the former two-handicapper having named his daughter in honour of Nick Faldo’s Masters triumph in Augusta, Georgia, in 1996.
Hall also fought back tears at the presentation ceremony as she dedicated the victory to her grandfather, saying: “There’s someone very special at home that’s going through a bad time so this is for you Grandad.”
Phatlum began the day with a one-shot lead over Hall and made a brilliant start with four birdies in the first six holes to double her advantage, even though Hall also birdied the first, fourth and sixth.
However, an errant drive on the eighth led to a bogey for the 28-year-old and Hall moved into a share of the lead thanks to a birdie from 10 feet on the 13th.
Both players birdied the par-5 15th after Hall’s eagle attempt from 15ft caught the edge of the hole and stayed out, but it did not take long for Hall to get her nose in front thanks to another birdie on the next.
When Phatlum then found sand off the tee on the 17th and compounded the error by three-putting for a double bogey, Hall had the luxury of a three-shot lead and could easily afford her only bogey of the day on the 18th.
“It’s too good to be true really,” said Hall.
“I don’t think it’s all sunk in for me. It was my goal when I was nine years old on the putting green: ‘This six-footer’s for the British Open’ and to actually have that – and luckily it was just a tap-in – I’m over the moon. I’m so happy.
“I promised myself not to get ahead of myself and feel any emotions, which is sometimes hard because I wanted to take it all in. I was staying very calm and patient and it was very close up to the last two holes and I was just trying to hole the putts.
“So many people were behind me and supporting me. It was so nice to play in England in front of a home crowd.”
Hall, who finished third in the British Open last year, added: “Last year was a learning curve for me and I got so much experience in the British Open and the Solheim Cup and I learned that I can play and compete against the best in the world.
“I was so confident coming into this event after last year.”
Sports Minister Tracey Crouch praised Hall’s performance, saying: “Congratulations to Georgia Hall on winning her first major in what was an incredible performance. Her victory is a great boost for women’s golf in Britain and I hope there are many more great things to come from her.”
Hall had briefly enjoyed a share of the lead when she birdied the first and although she also picked up shots on the fourth and sixth that was only good enough to stay in touch on 15 under.
Phatlum’s first mistake of the day proved costly, an errant drive on the eighth leaving her no option but to hack out sideways from thick rough.
The resulting bogey saw the 28-year-old’s lead cut to a single shot and Hall kept it that way thanks to a superb par save on the ninth after finding a greenside bunker with her tee shot. Both players had a chance to birdie the 13th and, after Phatlum missed her attempt, Hall took full advantage of being on a similar line to make the perfect read and hole from 10ft.
That took Hall into a tie for the lead and the 22-year-old saved par from a greenside bunker on the next to remain tied with her playing partner on 16 under.
Hall looked set to take the outright lead after a brilliant approach to the par-5 15th left her with 15ft for an eagle. But after Phatlum produced a superb pitch to two feet to set up a birdie, Hall’s eagle putt caught the left edge of the hole and stayed out, leaving the pair tied on 17 under.
It did not take long for Hall to get her nose in front for the first time all week, a birdie from 20ft on the 16th taking her six under for the day. A thrilling contest was then effectively decided on the 17th where Phatlum found sand off the tee and compounded the error by three-putting for a double bogey, leaving Hall with a three-shot lead that not even a bogey on the last could erase.