Evatt, a Spireite between 2003 and 2005, makes a surprise return to the club as a free agent having been released by Blackpool at the end of last season.
The 31-year-old told the club's official website: "I'm delighted to be back. My family is from around here and I know the area well.
"On and off the pitch, the club is run extremely well and they've got massive ambitions to become a Championship side. I want to do everything I can to help Chesterfield achieve this goal."
After starting his career with Derby, Evatt began his first spell with Chesterfield in 2003 when he was signed by Roy McFarland. He enjoyed two successful years with the club, winning the player of the year award at the end of his first season.
Evatt was sold to QPR for B£150,000 in the summer of 2005 and then joined Blackpool in January 2007. He was an integral part of the Tangerines side during their Premier League campaign and made over 200 appearances for the Seasiders before being released at the end of last season.