The acquisitions include the 77-bedroom Umi hotel in Brighton which will become Brighton Harbour Hotel & Spa, and Tides Reach on South Sands beach in Salcombe, the second property owned by the group in the Devon town.
In Bristol, Harbour Hotels acquired two buildings on Corn Street which were formerly the headquarters of Lloyds Bank and a Midland Bank site. The company plans to link the two buildings to create a 42-bedroom hotel with spa, restaurant and events space.
All new hotels will include the group's Jetty restaurant concept and its Harbour Spa brand.
Headed up by chef-patron Alex Aitken, the Jetty restaurant brand is a major champion of sustainable, local seafood and has won a string of awards.
Harbour Hotels managing director Mike Warren said: “These acquisitions further illustrate our ambitious growth plans; becoming one of the UK’s most exciting hotel brands. Expanding into cities such as Bristol and Brighton brings a new dimension to the group, with properties now featured in coastal, country and city locations.”