Known as the "golden boy with the golden boots", George Best helped elevate Manchester United to champions of Europe.
Stars from the film, including John Lynch, Linus Roache, Owen O'Neill, Marie Jones and James Ellis, will be among the stars who attended Monday's charity premiere.
The film goes on release throughout the UK and Ireland on 12 May.
The gala was screened at the Waterfront Hall in Belfast, but the hero of the film was not well enough to attend.
Known as the "golden boy with the golden boots", George Best helped elevate Manchester United to champions of Europe.
He is recognised as one of the world's best players and became one of the first "pop stars" of football.
The film, Best, was co-written by Mary McGuckian and John Lynch and developed with the cooperation of George Best.
According to Mary McGuckian, the challenge was how to make a film about a football player without making a football film.
She said: "Hopefully what we have achieved is a film that will appeal to football aficionados but at the same time have a wide appeal."
"What we would want them to come away from the film with is a rounded, full and complex sense of this man's life."
Charities to benefit from event
Some of Northern Ireland's great sporting heroes, including Barry McGuigan, Dave 'Boy' McAuley and Mary Peters, were also at the film's premiere.
The day's events kicked off on Monday afternoon with a pro-celebrity football match in the Blanchflower Stadium on the Holywood Road in Belfast.
Stars taking part included John Lynch who plays Best in the film, and actors Kenneth Branagh and Adrian Dunbar.
The celebrities took on a team of sportspeople including Mal Donaghy (ex-Manchester United), Ian Stewart (ex-QPR, Newscastle) and Irish rugby internationals Keith Crossan and Trevor Ringland.
The Northern Ireland Council for Voluntary Action and Cinemagic are to benefit from the premiere event.
Said Cinemagic's Richard Gaston: "It's a tribute to George's popularity that so many people are coming to Belfast to make this such a special occasion.
"I know that there are premieres planned for Manchester and London within a couple of weeks, but Belfast is first and rightly so.
"We have therefore worked very hard to show that, when it comes to celebrating sporting excellence nowhere does it better that Belfast."