Doubletree by Hilton London Hyde Park, located on Bayswater Road, has 228 rooms and DoubleTree by Hilton London Ealing has 189 rooms. The latter also has six meeting spaces, accommodating up to 240 banquet style.
Christopher Rawstron, vice president of operations for asset management for Westmont Hospitality, which holds the franchise agreement for both properties, said: "London has experienced a steady growth in the hotel market over the last few years and the initiation of an investment programme at both properties will ensure that these hotels will stay ahead of the competition.
"The revitalisation programme has been designed to give guests a warm welcome and stylish accommodation, marking a new era for the hotels."
Patrick Fitzgibbon, senior vice president of development in Europe and Africa for Hilton Worldwide, said: "Building on the international exposure of 2012, we are thrilled to be enhancing our presence in London with these two latest additions and now have 38 hotels open and under development right across the city and its airports."