The former Ramada hotel is located two miles from Gloucester city centre and includes eight conference and event spaces.
Facilities also include a pool, health club and beauty salon. Hallmark Hotels is planning to upgrade the hotel from its current three stars to bring the property in line with the rest of the four-star Hallmark collection.
Hallmark Hotels managing director Arnold Schnegg said: "Hallmark Gloucester is a fantastic property in a great location and will make an excellent addition to the Hallmark portfolio. The refurbishment will begin in January 2011 and in the mean time we will be bringing the service and standards up to the level our customers expect from our hotels."