The Fresno Police Department says it happened just before 7 pm Thursday near Maroa and Shields.
Police say the motorcyclist was going north on Maroa when it collided with the van.
Authorities say the motorcyclist suffered life-threatening injuries and had to use a tourniquet on their legs.
They were taken to Community Regional Medical Center and rushed into surgery.
No one else was injured.
The driver of the van stayed at the scene and is cooperating with investigators.