The 10.4 million development – which is expected to create about 50 jobs when open – is part of the company's plans to increase the number of Premier Inns in Scotland from 53 to 62.
The nine sites already under construction or in development are set to create about 420 jobs at a cost of more than 42m.
Whitbread said its West Nile Street hotel will be the first office-block-to-hotel conversion project in Scotland to benefit from the business premises renovation allowances scheme, a UK government initiative to encourage the conversion and renovation of empty properties.
Projects already announced as part of the 42m scheme include three hotels in Edinburgh – at the airport, in Princes Street and at the Edinburgh Park office development – two in Inverness and one each in Dalkeith, Dumbarton and Falkirk.
Whitbread's restaurant brands include Beefeater, Brewers Fayre, Costa Coffee and Table Table.