Edwards, who was the second-to-last driver to make his qualifying attempt in the 45-car field, posted a lap at 179.452 mph around the fast 1.54-mile Atlanta track. He earned his fifth pole of the season and the 26th of his Nationwide career.
Brad Keselowski secured the outside pole with a lap at 178.075 mph. Keselowski, the 2010 series champion, is making his first start in the series since suffering a broken left ankle and a sore back from a crash while testing one month ago at Road Atlanta.
Ricky Stenhouse Jr., the current points leader, grabbed the fifth starting position.
Stenhouse holds just a five-point lead over Sadler and a 10-point advantage over Reed Sorenson, who will start 12th.
Brian Keselowski and Mike Harmon failed to qualify.
The 300-mile race at Atlanta is scheduled to start just after 7:30 p.m. (et).