Police had been searching for Mr Morris since he was reported missing at around 6pm on Saturday (December 7).
The 51-year-old had last been seen in Blackpool Old Road, Poulton and his family had described his disappearance as "very unusual".
At around 11am yesterday (December 19), police were called to reports of a possible casualty on a mud bank in the middle of the River Wyre, near the former ICI site in Thornton.
Fleetwood and Knott End Coastguards and RNLI lifeboat crews were called to the scene and the body was brought to shore and taken to Fleetwood Lifeboat station.
This morning, Lancashire Police confirmed that the body is believed to be that of Simon Morris.
"His family have been informed and our thoughts are with them at this time.
"We would like to thank everyone who assisted during the search for Simon."
Police said his death is not being treated as suspicious and a file will be passed to the coroner.
HM Coastguard Fleetwood said the recovery of the body was "a very difficult and prolonged operation" due to low tide and mud banks.
A spokesman for HM Coastguard Fleetwood said: "The team, along with Knott-End Coastguard Rescue Team were paged to assist Lancashire Police and Fleetwood Area Police following reports of a possible casualty on a mud bank in the middle of the river.
"Coastguard Rescue Teams started to try to gain access to the casualty but had major difficulties due to the terrain consisting of deep gullies and mud banks.
"Although the casualty could be seen from a distance on the Knott End side of the river, we had difficulties with access to the area at low tide with deep gullies and extremely deep mud banks.
"Also, due to the perspective and bend of the river at this point, an exact location from the Fleetwood side which allowed safe access was difficult to ascertain.
"Using a Police Drone, identification was also not possible due to distance limitation from the drone operator.
"As the tide started to flood, further assistance was requested from NPAS (National Police Air Support) who spotted the casualty and directed RNLI Fleetwood, who launched their lifeboat to the exact location.
"The casualty was recovered by the lifeboat crew and passed over to the police.
"Despite a very difficult and prolonged operation, officers from several police teams as well as coastguards and lifeboat crews worked extremely well to bring this operation to a timely end.
"Our thoughts are with the friends and family of the casualty."