The contract is the first exclusive deal GECFS has done with a remarketing firm, and will run for two-and-a-half years.
It involves selling end of contract cars for GE Capital Fleet Services (GECFS) and vans for GE light commercial vehicle subsidiary TLS.
Auctions will take place at 10 venues around the UK, and online.
Mike Hallam, GECFS's UK remarketing director, said: 'We have undertaken a review of our global marketing requirements and have appointed Manheim in recognition of its innovative online remarketing systems, and its ability to provide proactive ideas and solutions to our disposal needs.'
As part of the deal, GECFS will have access to all Manheim's services.