The Northern Ireland international has joined the Spireites’ title crusade, days after the impressive capture of midfielder Tom Naylor from Wigan Athletic.
Grigg - who went global with his catchy terrace tune in 2016 - signs from MK Dons on a three year contract.
The 31-year-old will be looking to get the goals to fire the club up.
After losing May's Promotion Final to Notts County, Chesterfield hope to go one better this time around.