University of Greenwich has been granted permission to knock down a 1990s conference centre on the site and replace it with the new three-storey building.
The extension will be added to the grade II listed Devonport House, which was built in the 1920s.
The two buildings will be connected by an “internal street” covered by a glass atrium roof, allowing the façade of the listed building to be exposed.
The new building will contain a 90-seat lecture theatre and a 150-seat lecture theatre for the university.
Devonport House itself will be refurbished under the proposals, with a grade II listed war memorial relocated to a garden at the front of the site.
Greenwich councillors agreed to approve the plans at a meeting held earlier this month.
Historic England raised no objections to the plans, which it described as a “visually discrete addition” to the World Heritage Site.
The conference centre was part of the former hotel, but has been used by the university as a teaching space in recent years.
