The 65-year-old was hit by a Ford Transit as he tried to cross the A82 road in Dumbarton at around 5.20pm yesterday.
He was taken to the Southern General Hospital in Glasgow but died earlier today.
The 29-year-old driver of the van and his male passenger were uninjured but badly shaken, police said.
Inspector Adam McKenzie said: "Inquiries into the crash are continuing today, and I would ask any witnesses, or anyone with information that may assist police inquiries, to contact Police Scotland on 101."
A report is to be sent to the procurator fiscal.