The collision happened at around 5.50am yesterday on Aberdeen's King's Gate, near the junction with Forest Road.
The 29-year-old rider of the Honda bike was taken to Aberdeen Royal Infirmary, where he died a short time later from his injuries.
Police Scotland said the road was closed to allow investigations to take place at the scene.
Anyone who witnessed the collision or may have seen the motorcycle in the area is asked to contact police on 101.
Elsewhere, around half an hour later there was a fatal road traffic collision on the A9.
The one-vehicle crash happened about three miles south of Dalwhinnie in the Highlands at around 6.20am.
It is understood one occupant was killed in the crash.
The A9 at Dalwhinnie was closed to traffic in both directions following the incident. Motorists were asked to avoid the area as the road was expected to remain closed for some time.
Meanwhile, a woman in her eighties has been taken to hospital after being hit by a car in Angus. She was struck on Saturday morning by a Ford C-Max car, and taken to Ninewells Hospital, Dundee, where she is being treated. Police Scotland is appealing for witnesses to call 101.