The former Central Hotel was built in 1883 and is located above the city’s Glasgow Central train station.
Principal Hayley has worked closely with Historic Scotland and interior designers Charles Leon Associates and Crerar & Partners architects to preserve the hotel’s original features including Italian marble floors and intricate cornicing.
The ceiling in the grand ballroom has also been raised by three metres, uncovering a set of windows that had been blocked for decades.
Principal Hayley chief executive Tony Troy said: "The £20m refurbishment of the Central Hotel has been a major project for us this year and it’s great to see the transformation complete. The hotel is a major part of Glasgow’s history and we are looking forward to the next chapter."
The hotel has 186 guest bedrooms, a chic champagne bar overlooking Central Station, a grand ballroom called The Grand Room of Glasgow and 21 flexible meeting rooms.