The 57-year old was using the ATV to do yard work on his property, located in the 20200 block of Robin Lane NE, when his wife realized she could no longer hear the vehicle's engine.
She went outside to check on him just before 7 p.m. and found him unconscious and trapped underneath the vehicle, according to Scott Wilson with the Kitsap County sheriff's office.
Wilson said it appears the man crashed into a tree and the ATV rolled on top of him.
Medics were able to move the vehicle and began CPR on the man. He was taken Raab Park in Poulsbo and then airlifted to Harborview Medical Center.
The man suffered life threatening injuries.