St John's Cathedral Catholic Primary School was built in 1882 to accommodate Portsmouth's rapidly increasing congregation of Roman Catholics. It replaced a Chapel built in 1796 in Prince George Street, half a kilometre to the west. The school is situated in the heart of the City of Portsmouth. Close by is the Royal Navy and Heritage Museums and it is only a few minutes walk away from the new Gunwarf Development.

The Cathedral is the Mother Church of the Diocese of Portsmouth, which was formed in 1882 and its present Bishop is Bishop Crispian Hollis who lives on the Cathedral site. Although he spends much of his time visiting the parishes of the Diocese, he is very much a part of the Cathedral life and well-known to Cathedral parishioners.