The former professional footballer from Greenock has teamed up with fellow Scots James McAvoy, Gordon Ramsay and Kevin Bridges, as well as Welsh actor Michael Sheen, Westlife's Nicky Byrne and comedian Patrick Kielty for this year's Soccer Aid to raise money for Unicef.
Compston's team - the Rest of the World - will take on England, under the watchful eye of Chelsea boss Jose Mourinho in a match today at Old Trafford.
The England squad includes comedian Jack Whitehall, actor Dominic Cooper and singer Olly Murs.
Compston began his career with Greenock Morton before landing a lead role in Ken Loach's Sweet Sixteen.
Despite his celebrated on-screen performances, having the opportunity to train with Mourinho - known as The Special One - will go down as one of his greatest moments, he says.
The actor had to miss out on some of the Soccer Aid training because of a knee and groin injury - but begged to be patched up and put on the pitch.
The Rest of the World team say their Portuguese boss has been studying previous charity clashes and has armed himself with a gameplan.
Compston said: "I nearly fainted the first night we came and Mourinho was shaking all our hands and he said to me: 'I hear you're a player.'
"It was one of the best things I've heard in my life. He says he's watched all the previous ones, he says he knows their weaknesses, he's got dossiers, he's got us doing drills.
"We all know already the part we've got to play in the game. I know where I've got to be in corners, I know where I've got to be at free kicks so it's been amazing."
Compston said the Scottish contingent in The Rest of the World line-up meant it was likely to get feisty. "Those three lions on a shirt are like a red flag to a bull," he said. "As a Scotsman you just want to go for them. We're not losing sight of why we're here. But you know, I didn't come here to get beat."
He said that winning the game "would probably mean more to me" than appearing in a Hollywood blockbuster.
"That's the perverse thing - that would probably be the greatest thing," Compston added.
The actor has spoken out in support of independence and says he "absolutely" believes that the two countries could work in partnership off the pitch if Scotland votes for independence.
Compston spends much of his time recording film and TV roles in London and the rest of the UK and doesn't believe his opportunities would be damaged.
"Nothing about this (independence) is anti-English - probably my favourite city in the world is London," he said. "My best friend is English. It's just about getting a government we vote for."
He believes independence is on the horizon as "people are tired of being told what they can and can't do". He added: "I think it's going to be close but I honestly think we're going to take it at the post.
"We're an amazing wee country with amazing resources and mainly it's the talent of our population."
Compston, who has starred in The Wee Man - the controversial film based on the life of Glasgow gangster Paul Ferris - as well as acclaimed ITV thriller The Ice Cream Girls, is about to start filming Robert Carlyle's directorial debut, The Long Midnight of Barney Thomson, alongside Emma Thompson.
Next year he will start filming the third series of BBC police corruption drama, Line of Duty. "I love the cast," he said. "Vicky McClure, Adrian Dunbar - our little team has become very close and Vicky is one of my best pals.
"I'm not a great one for being tied down but I'm already looking forward to getting back to the third and fourth series."
Soccer Aid 2014 will raise money for Unicef to help some of the world's most vulnerable children. For information or to donate visit www.unicef.org.uk/socceraid. All public donations will be matched by the UK Government.