Mr Johnson unveiled a plaque in the reception hall of the new building, which is situated within the historic Winter Gardens, on the second and final day of the Conservative Party Spring Conference.
It is the first time the Conservative Party has staged a major conference in the resort since 2007.
The new state-of-the-art conference centre has been designed so that it seamlessly integrates with the Winter Gardens complex.
With 2,400sq metres of dedicated space set over two floors and equipped with cutting-edge audio- visual technology, the new build adds a unique contemporary twist to the Winter Gardens, which first opened in 1878.
With a direct link into the Empress Ballroom, Opera House and Empress Buildings, the new centre has created a hub of 12 distinct venues, giving a total capacity of 7,000 delegates and almost five acres of connected conference, meeting, event and exhibition space.
Built on the site of a former car park, the scheme was facilitated by £17.8m of funding from the Government’s Growth Deal, which is managed by the Lancashire Economic Partnership (LEP), almost £3m from the Coastal Communities Fund and the remainder from Blackpool Council and the Blackpool Entertainment Company Ltd (BECL).
It is the first major building development at the Winter Gardens since the construction of the Opera House in 1939.
After officially opening the centre, the Prime Minister said:
Since being acquired by Blackpool Council, the original Winter Gardens buildings are undergoing a multi-million pound upgrade with a new air-conditioning system, improved digital connectivity and extensive refurbishments to restore rooms such as the Floral and Spanish Halls back to their original splendour.
Cllr Lynn Williams, Leader of Blackpool Council said:
Michael Williams, Managing Director of BECL, the company that operates the Winter Gardens, said:
Debbie Francis OBE, Chair of the Lancashire Enterprise Partnership, said: