Antetokounmpo, who would had been able to enter free agency next year, said in a statement on Twitter he had agreed a five-year deal with the Bucks, AFP reported.
"This is my home, this is my city," the 26-year-old two-time NBA MVP said. "I'm blessed to be able to be a part of the Milwaukee Bucks for the next 5 years. Let's make these years count. The show goes on, let's get it."
ESPN reported that Antetokounmpo's contract extension was worth $228 million. The deal allows an opt-out after four years. ESPN reported that the contract was the biggest in NBA history, eclipsing the $206.8 million five-year deal agreed between Russell Westbrook and the Oklahoma City Thunder in 2017.
The deal will also see Antetokounmpo pocket the highest average annual salary in the NBA over the length of the contract, ESPN reported. Antetokounmpo will earn an average $45.6 million a year. LeBron James earns $44.5 million a season with the Los Angeles Lakers.
The eye-watering contract marks the latest chapter in the rise of Antetokounmpo, who was born in Athens to Nigerian immigrants and once earned money hawking watches, bags and sunglasses as a street vendor.
After taking up basketball as a youth, he was eventually spotted by NBA scouts and drafted with the 15th overall pick by the Bucks in 2013. He made his league debut as an 18-year-old later that year.
Antetokounmpo has dominated the NBA in recent seasons, winning the season MVP honors this year as well as the defensive player of the year award, averaging 29.5 points and 13.6 rebounds per game.
However Antetokounmpo's dominance has not translated into championship success for the Bucks, who were eliminated in the Eastern Conference finals by Toronto last year before falling to Miami in the early rounds of this year's playoffs.
The Bucks continued failure to reach the NBA Finals had led to speculation linking Antetokounmpo with a move to a proven championship contender.
The Golden State Warriors have consistently been linked with Antetokounmpo, while the Lakers were also reported to be circling.
However, Antetokounmpo had consistently said he would be open to staying in Milwaukee provided the franchise was in a position to challenge for championships.
"I don't see why not to be in Milwaukee for the next 15 years," he said in September.
Antetokounmpo also made clear that winning back-to-back NBA MVP awards was no consolation for failing to land a title with the Bucks.
"I'm happy for this award, but I want more," he said after winning the MVP award in a landslide. "I want to be a champion."