Michael wore the tailored two-piece with a crisp white shirt and a complementary patterned navy tie.
Jack Reynor and his partner Madeline Mulqueen attending the UK premiere of Macbeth at the Festival Theatre in Edinburgh
Earlier in the day, the stars of the movie attended a photocall at Edinburgh Castle with a beautiful scenic backdrop
Main man Michael opted for a more casual look that at the promotional event as he wore a suit with an open necked white shirt and brown brogues while having a laugh with his co-stars.
The eagerly-awaited film, by Australian director Justin Kurze, was screened to critical acclaim at Cannes earlier this year.
Fassbender, who played Irish revolutionary leader Michael Collins in the play Allegiance during the 2006 Edinburgh Festival Fringe, said he reimagined Macbeth as a battle-weary soldier suffering from post-traumatic stress disorder, which fuelled his descent into madness and murder.
His take on the role is being tipped as a career-best performance that could earn him his second Oscar nomination.