Minerva House was built between 1979 and 1981 for Grindlays Bank. As well as offices, it includes 12 flats which would be unaltered by the proposed scheme.
The building was purchased by Great Portland Estates 11 years ago for £60 million.
One of Minerva House's current office tenants – law firm Winckworth Sherwood – recently announced a move to the Arbor building in Blackfriars Road, recently constructed as part of the Bankside Yards development.
Great Portland Estates plans to add two storeys to the building and infill the courtyard. The scheme has been designed by Ben Adams Architects and was considered by Southwark Council's planning committee on Tuesday night.
Introducing the application, planning officer Zaib Khan said that the extra storeys had been "designed in a modern, predominantly glass and metal finish".
As well as new retail space at ground level, the scheme will create a new cut-through between the end of St Mary Overie Dock and Cathedral Street for use by people following the Thames Path and Jubilee Walkway.
Mr Khan said that the scheme's design had been tweaked since it was first submitted to the council to reduce its impact on the setting of Southwark Cathedral.
The council's archaeologist has advised that there is "potential for archaeological remains of national significance" to be present on the site and has recommended that the developer is required to put on a "programme of public engagement" to share any discoveries with the public.
Recommending that councillors approve the scheme, Mr Khan praised its "high design quality" and limited impact on nearby historic buildings.
The committee heard that the developer will make a £425,000 contribution towards works at Southwark Cathedral – including accessibility improvements – to mitigate the impact of the office development.
Speaking in objection to the application, Amir Eden, executive chair of Living Bankside, said that the scheme offered "no direct tangible benefits which will meet the needs of the people of Southwark".
"We should not be accepting investment which seriously and negatively impacts our ability to create exemplary neighbourhoods," he said.
He added: "The cathedral and its surrounding conservation areas are Southwark's crown jewels. How can we honestly say we care about – and want to protect – our heritage when application after application is being approved demeaning the fabric and the character of the conservation areas?"
James Shipton from Great Portland Estates told councillors: "Our reuse proposals provide an opportunity to minimise the embodied carbon by retaining 70 per cent of the existing structure, significantly improve the energy efficiency as well as provide new green spaces and enhance biodiversity, making an exemplary contribution to addressing the climate emergency.
"Our net zero carbon proposal reuses 12,000 sq m of existing office space and creates a further 6,000 sq m of new space."
He added: "Overall, it is estimated that the improved building will support more than 1,600 jobs, boosting the local economy and responding to the council's priorities for the area."
Borough & Bankside ward councillor Irina von Wiese addressed the meeting to object to the application.
Among the issues she raised was the impact of the proposed new retail space in the development.
Cllr von Wiese warned that some of her constituents are reaching "a tipping point … where many people can take no more" given the cumulative impact of the growing number of food and drink outlets in the area and related alcohol-fuelled antisocial behaviour.
Committee member Cllr Kath Whittam welcomed the scheme: "Minerva House at the moment looks horrible and I think it will improve the look," she said.
Planning chair Cllr Richard Livingstone said the revamped building had "design merits" and would be "better suited to the area".
The committee resolved that planning permission be granted, subject to referral to the Mayor of London.