Former Manchester United and Real Madrid midfielder Beckham, speaking on his first-ever visit to India and in his role as a UNICEF Goodwill Ambassador, admitted he still has to pinch himself when he sees the Argentinian World Cup winner on the teamsheet in Florida.
"It's still hard to believe that when someone turns around to me and says Inter Miami have Lionel Messi in their team, you know," he said.
"It's a very proud thing for me to have as an owner, to have a player like that, the best player in the world, in our team.
"We always knew that bringing Leo to America, not just to Miami, it was our gift to America and the MLS.
"Because someone like that changes the game. You know, someone like that inspires another generation of soccer players.
"And that's why we wanted to bring Leo to the team. Of course, we want to win championships. Of course, we want to be the best team in the league.
"But one of the reasons why we bought him was to also inspire the next generation of soccer players in America.
"To want to be soccer players. So bringing him does that and it's an important thing for us."
Former Barcelona and Paris Saint-Germain star Messi shocked the football world when he shunned stratospheric offers from Saudi Arabia and elsewhere to join Inter Miami in July, seven months after he had led Argentina to World Cup glory in Qatar.
He went on to light up Major League Soccer with some stellar performances but was unable to carry Inter Miami into the playoffs this season.
'Faces light up'
Beckham, who has turned a successful playing career that included captaining England and winning the Champions League with Manchester United into a high-profile role as a rights advocate and style icon, is the co-owner of Inter Miami.
He was speaking to AFP in Mumbai before attending the start of the Cricket World Cup semi-final between India and New Zealand, in an interview for which questions had to be vetted in advance.
Beckham explained that his first contact with the UN children's charity began when he was a teenager.
"My first involvement with UNICEF was when I was 17 years old in Thailand when I was there with Manchester United, and I went to a women's care centre," he said.
"But obviously with my travels over the years, I've seen how young girls are getting left behind, they're not getting the same rights and the same equal opportunities as the boys.
"So our focus has really been on girls in the last five to 10 years and that is the same here."
Beckham said he was convinced sport could play a key role in children's lives, as it had in his own.
"It gave me the foundation to have leadership, teamwork, discipline, focus. And just to have that confidence," said the father of four children.
"I've seen when I've gone into different villages around the world with UNICEF when I take a football into this village, these children's faces light up.
"For that time when I'm playing football with them or they're kicking a football around, they forget about everything else that is going on around them that is not good."
