Developers Rockwell bought the 10-storey 1980s office block in 2020.
The Salvation Army is moving its UK headquarters from Elephant & Castle to the William Booth College site in Denmark Hill.
Now Rockwell's plans for the site – drawn up by architects SimpsonHaugh – have been made public.
The scheme includes two towers: a 325-bed hotel in a 23-storey building and 250,000 sq ft of flexible office space in a 25-storey block.
The architects claim that the building's facade design takes cues from both Metro Central Heights and the nearby TwoFiftyOne tower.
The developers' feedback form at www.101newingtoncauseway.co.uk is open till 7 August.
A planning application is due to be submitted to Southwark Council this autumn, and if the scheme is approved, work could be complete by winter 2025.