Check out Newsround's quick guide to Britain's heavyweight boxing champion.
Anthony Joshua was born in Watford, Hertfordshire, and is one of Britain's best professional boxers.
The 27-year-old's mother is from Nigeria, Africa, and his father is from Britain.
Joshua was sports-mad from a very young age.
He was brilliant at football and athletics and broke the Year Nine 100m record with a time of 11.6 seconds.
Anthony decided to get really serious with boxing at the age of 18 and joined a local club.
Anthony became very good at the sport of boxing very quickly, and had won all 18 fights at amateur level during his early 20s.
He soon set a goal to become an Olympic champion.
In 2012, Joshua won the gold medal in the super heavyweight category at the London Olympics.
He became a professional boxer in July 2013, which means he started earning money for taking part in matches.
Joshua used some of that money to buy his very first boxing club, Finchley ABC, some new equipment.
He said: "This is where I started so I also donated some of my memorabilia in the hope that, when the children see it, it will inspire them to dream big."
Well boxing is pretty complicated, there isn't just one heavyweight championship - there's four major belts up for grabs offered by different organisations.
He won his first belt, the IBF heavyweight championship in April 2016.
On 29 April 2017, Joshua won a boxing match against Ukrainian boxer Wladimir Klitschko to add the WBA title to his collection.
The victory means that Joshua now holds two of the four major world championships on offer in the heavyweight division.
Anthony Joshua beat Wladimir Klitschko on Saturday night in front of 90,000 fans at Wembley Stadium, London.