Cox & Kings have sold Eurocamp to a French travel firm for almost £90 million as part of a restructure.
New owners Homair Vacances group acquired the subsidiary of Holidaybreak for £89.2 million.
The deal is subject to approval by the competition regulators in the UK and would mean the company operating 15,000 mobile homes throughout European holiday parks.
Peter Kerkar, CEO of Holidaybreak, said the mobile-home rental business was not a strategic priority for the group.
He said: "This sale will strengthen our balance sheet and the growth capability of our core businesses."
Holidaybreak was acquired by Cox & Kings for £312 million in 2011 and operates under various brands including PGL, Superbreak and Explore adventure holidays.
