The cathedral was built over a crypt, designed by Sir Edwin Lutyens, which was intended to be part of a grand classical-style building that began in the 1930s.
Construction was halted due to financial constraints and the outbreak of World War Two.
Catherine Croft, director of The Twentieth Century Society, a charity which campaigns to save modern architectural and design heritage, said the cathedral was “unique in world architecture and has long been a powerful homecoming beacon for Liverpudlians”.
She said Liverpool “now rightly has two magnificent Grade I-listed cathedrals”.
The existing Grade II listing for Hopwood Hall Chapel, which was built in 1964 according to Sir Frederick’s designs, was overseen by Reynolds and Scott.
The listing for the former chapel at Hopwood Hall College on Rochdale Road, Middleton, has been updated to recognise the “shared architectural significance” with the Metropolitan Cathedral.
