The collision happened shortly after 4pm yesterday in Huddersfield Road.
The Fiat Doblo van had been travelling in the direction of Thongsbridge when it came onto the footpath and was in collision with a wall and with the pedestrian, police said.
The casualty, a man aged 48, suffered serious injuries and was taken to hospital where he remains.
Police are appealing for witnesses, particularly anyone who stopped to give the injured man first aid.
Anyone with information can contact police on 101 or use the live chat facility www.westyorkshire.police.uk quoting crime reference number 13180522595.