French World Cup football champion Zinedine Zidane, Brazilian supermodel Adriana Lima, Formula One driver Nico Rosberg and tennis legend Boris Becker were other luminaries modelling luxury timepieces for the Richemont brand.
The IWC Schaffhausen Race Night was one of several events organized for the Salon International de la Haute Horlogerie (SIHH) at Geneva’s Palexpo exhibition centre.
The event, showcasing 16 watch brands, coincides with the Geneva Time Exhibition and numerous smaller events in the city’s luxury hotels, all geared to promoting watch sales, largely to dealers, journalists and collectors.
McGregor, who appeared at a similar night for IWC last year, was sporting a trim beard as well as a watch with a large dial.
The Scotsman posed affably for photos alongside Lima.
A smiling Spacey appeared in a bowtie for the red carpet event, featuring music and a motor racing display, which attracted 800 guests and journalists, IWC said.
The brand rolled out its new line of Ingenieur watches and highlighted its partnership with the Mercedes AMG Petronas Formula One team, which helps explain Rosberg’s presence.
The watches range in price from around 3,500 francs to more than 30,000 francs.
Around 12,500 people are expected at the SIHH, which runs until Friday.
The salon showcases mostly brands from the Geneva-based Richemont luxury group, such as Jaeger LeCoultre, Baume & Mercier, Mont Blanc, Piaget, Cartier and Roger Dubuis.
The five-day Geneva Time Exhibition, which winds up on Thursday, is displaying watches from more than 30 smaller Swiss brands at the historic Bâtiment des Forces Motrices, a renovated utility plant.
The salons offer an opportunity to introduce new watch models, some of them running into the hundreds of thousands of francs.
The events are viewed as a barometer for the health of the Swiss luxury watch industry in the run-up to the world’s largest watch show, Baselworld, running from April 25 to May 2.