The 30-year-old victim had been on a night out in the city centre on Friday when she was befriended by a man.
He walked her back to a serviced apartment where she was staying in The Headrow at about 4am. It was there that the sexual assault took place.
An amount of cash and a mobile phone were also stolen.
Detective Inspector James Entwistle, of Leeds District CID, said: “We are carrying out extensive enquiries into this incident and the victim is being supported by specially-trained officers.
“We have CCTV footage that shows a man arriving at the apartments and leaving some time later and we urgently need to identify him.
“We would ask that anyone who knows who he is or who has any information that could assist the investigation contacts us immediately.”
Anyone with information is asked to contact Detective Constable 5504 Emma Kelly at Elland Road via 101 or call the independent charity Crimestoppers anonymously on 0800 555.