The Spa 24 Hours was conceived by Jules de Their and Henri Langlois Van Ophem and debuted in 1924 over a 15 km circuit on public roads connecting the towns of Francorchamps, Malmedy, and Stavelot, under the auspices of the Royal Automobile Club of Belgium. The present Circuit de Spa-Francorchamps, measuring 7.004 km, was inaugurated in 1979 and has seen only minor layout variations since then.
The event served as a round of the European Touring Car Championship between 1966 and 1973, returned in 1976, and was again part of the ETCC from 1982 to 1988 (with the 1987 edition instead counting toward the inaugural World Touring Car Championship). It also counted toward the World Sportscar Championship in 1953 and the World Endurance Championship in 1981.
The race has attracted an extraordinary variety of machinery over the decades. Cars entered have ranged from Russian Moskvitch saloons and sub-1,000 cc NSU Prinz TT models to high-powered GT machinery. One of the most memorable entries was the Mercedes-Benz 300 SEL 6.3, tuned by Mercedes-AMG to produce 420 hp from its 6,834 cc V8 — nicknamed the "Red Pig" for its size and color — which finished as high as second overall in the 1971 edition.
The 1975 race was marked by tragedy when Dutch driver Wim Boshuis was killed after his car collided with others on track; a track marshal was also killed in a separate incident 30 minutes later, when Belgian driver Alain Peltier struck a railing.
The 2004 race produced a historic milestone when Swiss driver Lilian Bryner won as part of the BMS Scuderia Italia team on a Ferrari 550 Maranello, becoming the first female driver to be part of the winning team of a 24-hour endurance race in a Grand Turismo car exceeding 500 hp.
The 2020 race was held behind closed doors for the first time, due to the COVID-19 pandemic. In 2023, a scheduling conflict with the Belgian Formula 1 Grand Prix forced the Spa 24 Hours to be rescheduled to early July rather than its traditional late-July slot.
In its current form, the Spa 24 Hours operates as a GT race under FIA GT3 and GT3 Cup regulations, organized by the SRO Group. It has been part of the Intercontinental GT Challenge since the series' inaugural 2016 season. Cars competing span from GT3-specification race cars from manufacturers such as Ferrari, Porsche, Mercedes-AMG, Audi, BMW, and Lamborghini, to GT3 Cup variants.
The race also features the Coupe du Roi (King's Cup), awarded to the best manufacturer based on a points tally across all entered cars of the same make — not necessarily the race winners. An Australian manufacturer, Holden, famously won the Coupe du Roi in 1986 despite their cars finishing 18th, 22nd, and 23rd outright.
The Spa 24 Hours is one of the cornerstones of European GT and touring car racing, sharing with the Nürburgring 24 Hours the distinction of being a major 24-hour event on a historically demanding European circuit. Its longevity — nearly a century of continuous history — and its setting on the iconic Spa-Francorchamps layout give the race a prestige that extends well beyond the GT category. The combination of Eau Rouge, Raidillon, Pouhon, and the Ardennes weather conditions makes the race as much a test of car reliability and team strategy as raw speed.