Police were contacted at 8.30pm after the man, from Horsham, said he had been struck as he tried to cross the road.
He was taken to East Surrey Hospital with a suspected fractured ankle.
The vehicle did not stop after the crash.
PC Ben Henwood said: “I’d like to speak to anyone who was in the area at the time and saw the accident or the vehicle leaving the scene afterwards.
“If you have any information at all please contact us.”
Sussex Police are appealing for witnesses. Anyone with information can call 101 quoting serial 1378 of 8/1 or email [email protected]