Police, coastguard and ambulance teams were called to Ryde in the early hours of this morning (Friday) after receiving reports of a man entering the water near to the pier.
After being pulled from the water just after 12am, the man was taken to St Mary's Hospital having suffered serious injuries.
A spokesperson for Hampshire Constabulary said:
"We were called out at 12.05am this morning (Friday) following reports of a concern for welfare after a man was seen to enter the water by Ryde Pier.
"Officers, along with the coastguard and paramedics, attended the scene and a man was extracted from the water.
"He was taken to St Mary’s Hospital for treatment after suffering serious injuries, but not believed to be life-threatening."