It happened just before 5 p.m. in the 2200 block of South Plank Road near the Church of God of Prophecy.
Authorities say a 1989 Chevy pickup driven by 29-year-old William Lamonds was driving south when the lawnmower operated by 55-year-old Otis Earl Colvin III went into the southbound lane and was hit by the truck.
Colvin was mowing the grass in front of his home. He was thrown onto northbound shoulder of the road and died at the scene.
No charges will be filed.