Officers were called to Ashey Road during the early hours when an individual was found with injuries at the side of the carriageway.
Paramedics from the Isle of Wight Ambulance Service were dispatched to the scene and treated the male for his injuries.
A section of the road has been sealed off between Bettesworth Road and Leighwood Close as investigations get underway.
A shoe can be seen in the gutter, with a garden railing damaged nearby.
Specialist traffic officers from the mainland have been called in to examine the scene and determine the next steps in the investigation.
It is currently unclear whether any vehicles were involved but it is a line of enquiry Police are following.
Motorists are having to divert locally and with Upton Road closed, the only alternative route is via Binstead and Wootton – or Smallbrook Lane to The Downs.
Hampshire Constabulary has been approached for a statement.
UPDATE @ 07:05 – The cordon has been extended to include the entrance way to Ashey Place.
Island Echo is told that the Forensic Collision Investigation Unit is en-route to the Island to continue on-scene investigations.
Southern Vectis says that their Route 37 are on diversion. Buses will divert from Ryde Medical Centre along Binstead Road, Newnham Road to Kings Road to resume normal route until further notice. Bus stops from Ashey Roa to Newnham Road South cannot be served.
The road is expected to remain closed for several hours, including during the busy school drop-off period.
Haylands Primary School should be accessed via St Michael’s Avenue, or the lower half of Ashey Road. Parents cannot walk down Ashey Road to Bettesworth Road.
UPDATE @ 08:40 – Police have confirmed that they are investigating a hit and run incident involving a car and a pedestrian.
Read more on this incident at https://www.islandecho.co.uk/police-hunt-car-with-front-end-damage-following-hit-and-run-in-ryde/.
UPDATE @ 16:27 – Ashey road has now reopened to traffic in both directions following the closure. Southern Vectis route 37 buses are expected to resume their normal routes shortly.