A man walking on a footpath has died after being hit by a ute that veered off a main road in Sydney's north.


Motorists have been advised to avoid Willoughby Road at Frenchs Road and Borlaise Street after Tuesday morning's incident due to expected traffic delays.


Police said officers were called to the scene shortly before 7.25am (AEST) where witnesses told them the utility crossed lanes of traffic before hitting a bin and a street sign, then the pedestrian.


The man suffered serious injuries and was treated by NSW Ambulance paramedics but died.


The male driver of the ute wasn't injured and was taken to hospital for mandatory blood and urine testing.


AAP