The diversity of Miami was a significant attraction for Beckham. "I was drawn to this city for the same reasons as millions of others. Diversity, culture, the weather, the beaches, the people," he said.
When he joined Los Angeles Galaxy in 2007, Beckham had the option to buy an expansion team for $25 million in his Major League Soccer contract. But a series of options for stadium venues fell through before land was finally secured in Miami''s Overtown area.
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There is an outstanding appeal from a local businessman who objects to the sale but a US$225m (£160m) stadium is now expected to be built and the team, which still has no name, will begin playing in 2020.
At the launch Beckham held a black and white scarf, which appear to be the colors of the new club.
"I was in from day one. I promise the team we bring in will be the best team," he said. "There were too many bumps in the road but I don't give up."
He compared setting up the club with when he was told he was "too small and skinny" to make it as a top player: "I had people come up to me and say let it go. The one thing that kept me going was you guys, the fans."
In response he was greeted by roars of "Miami, Miami" from hundreds of people at the venue.
Beckham first announced his intention to launch the team in February 2014. But the cruise industry blocked an attempt to build a stadium at the Port of Miami and subsequent attempts to acquire land near the Miami Heat basketball stadium and the Miami Marlins baseball stadium failed.
The Beckham business team includes Simon Fuller, and the Mas family, who are prominent Miami businessmen. Beckham said: "I think the fact that it has taken this long, the fact that it's taken four years actually has worked as a positive. I've really gotten to know the city."
The announcement included video messages from celebrities including Jay-Z, Will Smith, Jennifer Lopez, Usain Bolt, and Neymar.
In a video message Victoria Beckham said: "I look forward to spending much more time in Miami as a family." There were also messages from Beckham's children. "I'm so proud of you Dad," said Romeo Beckham while 12-year-old Cruz added: "I'm really excited to be in Miami and eat more cabanas."
Don Garber, MLS commissioner, said he was confident the remaining litigation regarding the stadium would be overcome and explained that although the team name would be chosen through a process involving fans, and a branding agency would be brought in, but Beckham would have an input.
Establishing the team, he said, had been "very difficult"and "we started losing our own energy". Beckham had originally been offered the chance to buy a franchise, he revealed, because "we were not able to pay him remotely what he was paid at Real Madrid".
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