The motorcycle collided with an SUV near the intersection of California Ave. SW and SW Oregon St. just after 3 a.m., Seattle fire officials said.
Seattle police say a patrol officer was near the scene, heard the crash, and found a Jeep Liberty going south on California had collided with a motorcycle that had been westbound on Oregon.
Medics attempted CPR on the motorcycle rider, but he was later pronounced dead at the scene.
Police evaluated the SUV driver and found no signs of impairment from drugs or alcohol.
The victim's name has not been released.