The pair previously worked together at the Spireites when they lifted the 2010/11 League Two title.
The Welshmen was also part of Dean Saunders backroom staff in 2015 and was most recently with relegated Notts County before his contract expired last month.
"It is great to be back at Chesterfield and I'm really looking forward to working with John again," Crossley, known as 'Big Norm' told the club's website.
"It promises to be an exciting season and I can't wait to get started."
Boss John Sheridan is certain on the impact a legend like Crossley can have on the team this season, adding: "Mark is a top goalkeeping coach who will be an excellent addition to the backroom staff, I'm delighted he has agreed to join us."
Chesterfield fans won't have long to wait before learning their fixtures for the coming season. All will be revealed on Wednesday 3 July.