The victim was mowing the lawn at a home on Smoke Rise Lane in Clinton when he slid down a hill, causing the mower to slide off the property and overturn around 11 a.m., Clinton Township Police said.
The victim was ejected from the mower, which then landed on top of him and partially submerged him into the mud, police said.
The man was freed with help from South Branch Emergency Services and taken to Robert Wood Johnson Hospital.
Click here to follow Daily Voice North Hunterdon and receive free news updates.