Laurence Knight, 33, was arrested on July 28 last year, after a woman reported being raped on the beach 11 days earlier, and was released on bail.
On Friday he was summoned to appear at Brighton & Hove Magistrates’ Court on June 23, Sussex Police said.
The sergeant, attached to Met Detention, has been suspended from duty.
Scotland Yard said he was off duty at the time of the alleged offence.
Chief superintendent Pete Gardner, in charge of Met Detention, said: “We know people will rightly be concerned to hear about this very serious charge against a serving police officer.”
He also thanked his Sussex colleagues for the specialist support provided to the alleged victim.
Mr Gardner added: “The Met’s Directorate of Professional Standards are fully aware and misconduct matters will be dealt with once the criminal proceedings have concluded. The officer is suspended from duty.”
Scotland Yard made a referral to the Independent Office for Police Conduct, who determined the misconduct investigation should be led by the Met.