The 16-year-old finished ahead of New Zealand’s Zoi Sadowski-Synnott - the reigning Olympic champion - and Miyabi Onitsuka of Japan, to lift the women’s slopestyle title at the Snowboard, Freestyle and Freeski World Championships in Bakuriani.
Brookes, who was in the silver medal position after her first run, landed the first Cab 1440 double flip to punch a score of 91.38 and seal Britain’s maiden slopestyle gold.
"I honestly feel like I'm going to cry. I've never been so happy in my life," she told reporters afterwards.
The teenager was too young to compete at Beijing 2022 but was encouraged to try the Cab 1440 - named after the celebrated skateboarder Steve Caballero - by her coach after falling over two points behind in her first run.
The incredibly complex move involves taking off backwards and making four rotations in the air while holding the board twice.
"My coach was like, 'You know what? If you want to win this, just try the 14’. I'd tried 1260 in practice and I came round and almost went 14, so I knew it was possible on this jump.
"I'd tried it once before and this is the first time I've stomped it, so I'm super happy."
'One of our own'
Brookes joined Team GB’s development team when aged just 10 and GB Snowsport head coach Pat Sharples hailed her achievement in Georgia as "next level".
"We all know Mia's got the talent but this is her first season on the World Cup circuit and her first World Championships.
"To land a run like that with all the pressure of a World Championships tells you everything you need to know about her."
