The in-form Magpies came into the match in fifth spot, having picked up 13 points from a possible 15 in the last month, and looked the more likely scorers early on.
Kyle Wootton curled a shot just wide for the visitors before Kristian Dennis drew a good low save out of Chesterfield goalkeeper Shwan Jalal.
However, against the run of play, Chesterfield hit the opener - which turned out to be the difference between the two sides - in the 27th minute.
Scott Boden's cross from the right found the unmarked Gevaro Nepomuceno at the far post, and he slid in to volley past Sam Slocombe.
That was the on-loan Oldham winger's first goal for the club and it proved to be the winner in front of a crowd of 5,432, as Notts struggled - and ultimately failed - to find an equaliser.
Here is Pride of Nottingham vlogger ARLukomski's take on the match.
Share your thoughts about this vlog on Pride of Nottingham by signing up to the website, visiting the forum and joining in the chat with hundreds of fellow Notts County fans.
Fancy showcasing your brand or business on Pride of Nottingham? Click here to find out more about sponsorship and advertising opportunities with us.