The German government will provide some $6.4 billion dollars in loan guarantees as well as $2.1 billion in temporary loans to keep Opel afloat.
Under the agreement, Magna will take a 20 per cent stake in Opel and the Russian-owned Sberbank will take a 35 per cent stake, giving their consortium a majority.
GM will retain a 35 per cent holding, while the remaining 10 percent will go to Opel employees.
The consortium plans to work together with Russian car maker Gaz to produce more than one million vehicles in Russia and Eastern Europe.
As part of the deal, all four factories in Germany will remain in operation, although Magna has said previously it will need to shed some 2,500 jobs.
Siegfried Wolf, a co-chief executive of Magna, said he expected the agreements would be signed with GM in five weeks time.
"We really have taken the risk that was necessary to show a commitment, and we are committed, otherwise we wouldn't have done this deal,'' he said.
Roland Koch, state premier of Hesse, cautioned that state assemblies in both Hesse and North Rhine-Westphalia - two of the four German states with Opel plants - would still have to endorse the agreement. He said he hoped that could be completed by Sunday.
Fighting off rival
The Canadian company, front runner in the race to snap up Opel from the beginning, fought off rival bids from Italian car maker Fiat and Brussels-based investment firm RHJ International.
GM's total liabilities of $185bn break down into:
$27bn in unsecured debt
$25.5bn in government and bank loans
$20bn owed on healthcare and pensions
$112.5bn in other debt
Fiat dramatically pulled out of talks on Friday saying it was unwilling to expose itself to "unnecessary and unwarranted risks" and that it had insufficient information on Opel.
The firm's boss, Sergio Marchionne, was philosophical about Magna's victory, telling reporters in Montreal that he was mainly focused on completing a merger with Chrysler.
"If the Opel transaction is not available for Fiat, life will move on. We will continue to work with what we have," he said, before the deal was struck in Berlin.
Fiat is on the verge of taking control of a 20 per cent stake in Chrysler, another troubled US vehicle manufacturer, pending the completion of restructuring in bankruptcy court in New York.
In total, GM employs about 55,000 people Europe-wide, including around 7,000 in Spain, 4,700 in Britain at Vauxhall, 4,000 in Sweden at Saab, 3,600 in Poland, 2,600 in Belgium and 1,800 in Italy.