Lancashire Constabulary were called at around 3.10am on Thursday (February 24) to reports of a man entering the sea.
The Coastguard conducted a search, along with a police helicopter, but the man has not been located and police are now calling for witnesses to come forward.
A spokesman for Lancashire Police said: "We were called around 3.10am on Thursday, February 24 to reports of a concern for safety in Blackpool.
"It was reported that a man had been swept out to sea, close to North Pier."
Anybody with information is asked to call 101, quoting log 0128 of February 24.