City chiefs have agreed that 131 new flats valued at between £200,000 and £500,000 can be built by Qinetiq on its site in Eastney, Portsmouth.
Allan Kidney, speaking on behalf of British Naturism, the official organisation for naturists in the UK, told a city council planning meeting that the beach, near Fort Cumberland, had been used by nudists since the 1940s.
He urged councillors to reject the plan or to call for Qinetiq to pay for screens or a new beach so naturists could continue their naked sunbathing without being overlooked.
But councillors said the nudist beach was not an issue the committee had to take into consideration.
Eastney Lib Dem councillor Terry Hall called for a deferral to at least allow a solution for the nudists, but this was not taken up by committee members.
Qinetiq's agent, Matthew Fox, said: 'The beach is not part of the planning application and we would have no objection to its continued legitimate public use.
'They are building new sea defences there because of the danger of flooding. If they build the wall a little bit higher it would act as a screen.'