The project will create a community meeting area as well as 14,500 sq.ft of shops and restaurants.
It was green-lit by Westminster City Council after Grosvenor promised to retain the building's historic features and install a large glass staircase.
Restoration work is set to begin in summer 2016 with the venue opening to the public in late 2017.
Craig McWilliam, executive director, London Estate, at Grosvenor Britain & Ireland said: “This is an exciting opportunity for Grosvenor to use its experience in restoring architecturally and historically interesting buildings to open up a new place for the public – and right in the heart of London’s West End.”
The former St Mark’s Church opened in 1828 and was declared redundant and deconsecrated by the Church of England in 1974.
It has been used as private events space One Mayfair since 2009, and was purchased by Grosvenor in 2014.
Grosvenor’s current developments include the £500m luxury Peninsula Hotel opening on Hyde Park Corner.
It also owns the site of cronut creator Dominique Ansel’s upcoming Belgravia bakery, set to launch in autumn this year.