MLS commissioner Don Garber said: "David was really a home run for us, to use a baseball analogy.
"And a lot of that has to do with him being quite the celebrity. If I was a sponsor, I would want him to represent me because he's just a quality guy.
"I would also hope to see guys like Ronaldinho and Thierry Henry, who has expressed interest in coming here at the end of his contract with Barcelona.
"I hope to see at some point, certainly during my tenure as commissioner, players like that in Major League Soccer. And with Beckham being successful and being signed, it's hard to imagine you wouldn't see players like that in MLS."