The opening comes before the launch of the Upper Deck space, a destination bar with views of HMS Belfast and surrounding London landmarks, including Tower Bridge, the Tower of London and City Hall.
Will Sales, general manager for HMS Belfast, said: "The redevelopment of the new entrance is one of a number of long-term improvements being made to the ship. This is an exciting year for HMS Belfast with not only the opening of this fantastic new Café Bar but we have the launch of the Upper Deck later in the spring too – a busy time ahead for us all."
HMS Belfast, is now permanently moored between London Bridge and Tower Bridge. It is the only surviving example of big gun armoured war ships built for the Royal Navy in the first half of the twentieth century and played a crucial role in protecting the arctic convoys and supporting the D-Day landings during the Second World War.