Banks kicked the bottom of fellow midfielder Jimmy Ryan's boot during the early stages of last weekend's Johnstone's Paint Trophy final at Wembley and scans have revealed ligament damage in his right foot.
He will miss the Spireites' final six League Two fixtures as Paul Cook's side look to seal promotion and maintain their challenge for the title.
It is hoped the 21-year-old will recover in time for the start of the 2014/15 campaign.
"It's heartbreaking for the lad," said Chesterfield boss Cook. "He was delighted to be selected at Wembley, it was a great occasion for Ollie and his family. He's now out for the season and he has to join a lot of other people cheering us on and willing us to win.
"He'll be back stronger and better - he's a good player and one of the bright lights for this club going forward so we all wish Ollie a speedy recovery."