Formula 1 supremo Bernie Ecclestone and his private equity partners at Genii Capital pulled out of the race for the marque late on Monday night, leaving the door open for Spyker's bid.
Shares in the Dutch manufacturer had been suspended yesterday pending the announcement, having risen more than 70 per cent since the start of the year on the back of bid speculation.
Spyker agreed to pay GM $74m in cash and $326m in preferred shares in the new company that will be set up as part of the deal.
The sale – which is subject to the Swedish government agreeing to guarantee a 400m (349m) European Investment Bank loan to Saab – is expected to be concluded next month.
Saab is one of four brands – alongside Pontiac, Saturn and Hummer – which GM is selling to allow it to concentrate on its core Chevrolet, Buick, GMC and Cadillac marques.
The deal is expected to save the jobs of many of the 3,500 staff who work at Saab's factory at Trollhaettan in south-west Sweden.
Spyker – which only produces several dozen handmade supercars every year and is yet to turn a profit – hopes to benefit from Saab's technical resources and distribution network, while Saab, with annual production of more than 90,000 cars, would get an injection of entrepreneurial spirit.
GM bought half of Saab in 1990, before taking full control of the car maker a decade later.
Swedish sports car maker Koenigsegg, backed by Beijing Automotive Industry Holding (BAIH), walked away from a deal to buy Saab in November.
BAIH later bought some car technology from Saab's 9-3 and 9-5 models to use in its own vehicles.
News of the Saab sale to Spyker came after sources revealed that China's Zhejiang Geely Holding Group will nearly double Volvo's annual global production with a new factory in Beijing as part of its plan to pull the Swedish car maker out of the red by 2011.
Zhejiang Geely, the parent company of Hong Kong-listed Geely Automobile, aims to complete the purchase of Ford's Volvo unit for up to $2bn by May, industry sources said.
Geely, China's largest privately owned car maker, plans to produce 300,000 Volvo-branded cars at a new factory in Beijing and nearly double its output of its own-branded vehicles as well, sources claimed.
Analysts warned that the 2011 break-even target could be a stretch for Geely, whose founder Li Shufu has outlined ambitious global goals but has no experience of running a foreign company.