Four days before the North American league launches its 19th campaign with Defoe set to play for Toronto, Garber stressed the need to keep top American talent as well as sign big-name global stars such as Beckham, who left Real Madrid for the Los Angeles Galaxy in 2007.
French star Henry joined the New York Red Bulls in 2010 and Defoe and USA midfielder Michael Bradley left Europe for Toronto this year.
Canadian rap music star Drake was among those who encouraged Defoe to move to Toronto while Beckham has spoken with NBA star LeBron James about being a part-owner of his Miami MLS expansion team and actress Eva Longoria took to Twitter to help San Antonio's bid for an expansion team.
"There's an incredible integration between sports and entertainment," Garber said. "It just adds a little bit to our credibility and ties into that millennial sports fan idea of what's hip and what's hot."
Relegation and a champion crowned from a season of matches rather than a playoff system, staples of most elite global leagues, are not foremost in Garber's mind, saying neither is in MLS' plans.
"We're going to need to configure our competition to where our broadcast partners are going to get the most viewers and that means playoffs," Garber said.
"We have got to be in a situation where our clubs are making money so we can invest in this business."
Expansion teams are coming to Orlando, New York and Miami with Atlanta and Minnesota prime contenders for future new clubs and Garber looking at attendance figures for pre-FIFA World Cup™ exhibitions and European club visits to US venues.
"If you don't have support for big games, you're not going to have support for MLS teams," he said.