The body was discovered at about 5.14am this morning on Canal Road in Bradford.
Emergency services attended and confirmed the man was deceased a short time later.
He is believed to be in his late twenties or early thirties.
Enquiries are ongoing to identify the man and the circumstances around his death.
Detective Inspector Mark Taylor, of Bradford District CID, said: “We are making enquiries in the area into the last movements of the deceased, who was wearing a green hooded top and black tracksuit bottoms.
“While we have not yet confirmed this we believe he was walking along Queens Road just minutes before, so we are asking anyone who may have seen a man in similar clothing in the area at about 5am today to contact us.
“We would also ask anyone who has a dash cam and was driving in the area at around that time today to check their footage to see if they can assist us with our investigation.”
Anyone with information which may assist can contact Bradford District CID on 101 or use the contact options on the West Yorkshire Police website. The log reference is 231 of 11 January.It