Drugs or alcohol were believed to be a factor in the crash.
State troopers responded to the scene, Highway 900 east of 148th Street, at about 9:40 p.m. after receiving a report of a serious crash.
The motorcyclist, a 56-year-old Bellevue man, was found dead at the scene. His name was not released pending notification of his next of kin.
A preliminary investigation found that the man was heading east on Highway 900 on a 2007 Kawasaki Vulcan when he overshot a curve east of 148th Street. He slammed into the guardrail, veered back into the roadway and slid to a halt in the lane of travel.
High speed and impaired driving were found to be the cause of the deadly crash.