Officers were called to the B2095 at about 3.05pm on Thursday 15 December following a collision between a car and a flatbed van.
Colleagues from the ambulance service attended and the young boy was airlifted to the hospital with life-threatening injuries.
Sadly, he died as a result of his injuries on Saturday 17 December. His next-of-kin is being supported by specialist officers at this time.
A 33-year-old man from Eastbourne has been arrested on suspicion of causing death by dangerous driving. He remains in custody at this time and is awaiting an interview.
In the meantime, police are appealing for witnesses to the incident.
Anyone who saw what happened or who has any dashcam footage is urged to email [email protected], quoting Operation Seville.
