The Coronet at Elephant & Castle has been added to the Theatre Buildings at Risk Register by the Theatres Trust.
The Elephant & Castle Theatre occupied the site on New Kent Road from 1872 and the current 1932 structure – which boasts Art Deco interiors – incorporates fragments of an 1879 building.
The building was used as a theatre until 1928 and remained open as a cinema until 1999. Since 2003 it has operated as a nightclub and music venue.
The Coronet is one of 48 theatre buildings across the UK to feature on this year's register published by the Theatres Trust.
The trust fears that the Coronet could be swept away in the redevelopment of Elephant & Castle.
The trust is a 'statutory consultee' in the planning process and must be notified of planning applications related to theatres.
"We are at risk of losing really important and historic theatre buildings as a result of neglect, development and demolition," said Mhora Samuel, director of The Theatres Trust.
"It's so sad to see theatres treated in this way. Some have been left to rot and are being destroyed by water damage and rampant Buddleia; others are at the mercy of developers."