Incentive travel visits are expected to increase during the wedding to witness the royal procession wind past sites including Westminster Abbey and Buckingham Palace.
Visit London is predicting that an additional 600,000 visitors from business and domestic sectors will descend on London for the wedding.
Johnson said: "The pageantry, excitement and fantastic atmosphere of a royal wedding against the historic backdrop of London’s world famous landmarks is a glorious occasion I would recommend to everyone."
The Cavendish chairman Ciaran Fahy, who is also chair of The London Regional Committee of The British Hospitality Association added: "Some of the five-star hotels close to Buckingham Palace are full or only offering multi-night packages. However from speaking to BHA London members, we are aware that there is plenty of availability in the major branded hotels in the city."
Park Plaza Hotels & Resorts general manager Greg Hegarty commented: "We have no doubt that London hotels will all have 100% occupancy over the royal wedding weekend, but at the moment there is still plenty of availability."