Bus route 78 - which links Shoreditch with Nunhead via Tower Bridge and Bermondsey - will be converted to double deck operation from early next year.
News of the change was confirmed this week by Mayor of London Boris Johnson in a written answer to a question tabled by Val Shawcross, the London Assembly member for Lambeth and Southwark.
"It is proposed to convert the route to double deck operation in spring 2011, when new vehicles are expected from the manufacturers," said the Mayor.
A test run was held in July which confirmed that double decker buses could successfully navigate the route.
"There have been longstanding problems with capacity and overcrowding on the 78 and I hope that the use of double deckers from next spring will improve this," says Val Shawcross AM.
"I'd like to thank SE1 readers who contacted me about problems on this bus service – this helped to build up a good case with TfL."
Route 78 is operated by Arriva. A new timetable was introduced on Saturday 16 October.