Mani Kurian, 50, of Eridge Road, Eastbourne, was convicted unanimously by a jury at Lewes Crown Court. He was also found guilty of five sexual assaults and one assault by beating.
A 21-year-old woman was raped as she walked on the upper promenade towards the pier in the East Sussex town at about 02:00 BST on 19 October 2014.
Court officials said Kurian would be sentenced on 26 February.
A man has been found guilty of raping a woman near Eastbourne Pier.