Police found the 24-year-old man dead at his flat in the Hyde Park area of the city after concern was expressed about his well-being.
The man has not been formally identified but detectives said he had last been seen in “early November”.
He was discovered at the flat in St John’s Close on Thursday afternoon.
Anyone with information should contact West Yorkshire Police’s Homicide and Major Enquiry Team by calling 101 and reference 849 of November 17.
Information can also be passed anonymously to Crimestoppers on 0800 555 111.