Nine-year-old George Emsley won two belts at the World Martial Kombat Federation (WMKF) championships in Malta.
The four-day competition saw more than 600 athletes from around the world compete in different disciplines.
And George took the tournament by storm winning two sports karate titles.
His mum Jane Emsley said she was extremely proud of her son’s achievements.
She said: “Martial arts is a huge part of George’s life. He dedicates all of his time to practising.
“He has worked so hard over the past five years and to win the two belts at his first world championships is amazing.”
George, of Sandringham Court, Streethouse, won the WMKF point fight title, which sees the first competitor to win a point crowned the winner. He then clinched the WMKF light continuous belt, where the athletes compete to score the most points during an allotted time.
George has previously won dozens of British and national championships and a European belt.
He trains five times a week at Andy Crittenden Martial Arts Centre in Doncaster.
Sixth dan and chief instructor Mr Crittenden said George is the youngest of his 26 world champions.
He said: “George trains incredibly hard and for a young lad he has earned the respect of the other members of the team for his work ethic and determination.
“More importantly he is a very polite and respectful lad who deserves all the success in the world.”
George, a pupil at Streethouse Junior and Infant School, showed his belts to his classmates during a special assembly.
Headteacher Charlotte Clerehugh said: “George continues to make us very proud.
“To become a double world champion is an amazing achievement.”
George is now preparing to compete in the Irish Open in March next year.