Menzies Hotels has bought eight Thistles from owner Curzon Hotel Properties for a total of £54m.
The hotel group will take control of 978 bedrooms spread across Birmingham, Luton, Swindon, Stevenage, Irvine and Manchester, as well as Gatwick and Aberdeen airports.
Menzies has also unveiled plans to spend £12m on refurbishing and repositioning the eight properties in line with its existing hotels during the next 18 months.
In March, Leisure CIT Group paid approximately £400m for 28 Thistle Hotels.
Menzies itself was bought by a conglomerate of investors including property magnate Robert Technguiz's investment vehicle R20 back in October 2006.
Tim Penter, chief executive at Menzies, said: "The acquisition of these eight hotels provided us with the ideal opportunity to continue to grow and develop our portfolio of properties. All the hotels are in prime locations improving our geographical spread across the UK."