Bell took the lead on the final restart and was leading when the caution flew when Josh Berry spun on the backstretch. The win was Bell's first at Atlanta and 10th career Cup win.
William Sawalich battled back through the field after getting spun and led Toyota with a third-place finish at Iowa Speedway on Saturday evening. Taylor Gray (seventh) put a second Joe Gibbs Racing Supra in the top-10.
The 2023 Cup Series champion from High Point, North Carolina, clocked in a pole-winning lap at 134.191 mph in 23.474 seconds for his third Cup pole of 2026 in Newton, Iowa.
The 39-year-old Sieg from Tucker, Georgia, clocked in a pole-winning lap at 131.436 mph in 23.966 seconds for his first O'Reilly Auto Parts Series career pole in his 423rd series start.