It was a fortunate win for Harvick, who was second on the final lap until leader Carl Edwards ran out of fuel and dropped back to 21st place.
Harvick crossed the line at the Phoenix International Raceway ahead of Kasey Kahne, championship leader Jimmie Johnson and Dale Earnhardt Jr.
The 37-year-old secured his fourth win at the Arizona circuit and the 23rd of his career.
Fellow title contender Matt Kenseth had handling problems with his car and finished in 23rd position.
Johnson (2384 points) is on top of the drivers' standings with Kenseth (2356) and Harvick (2350) the only two men that can overhaul him.
The season finale of the series will be at the Homestead-Miami Speedway on November 17.