Ward, who scored a hat-trick against Aldershot Town in midweek, ran onto Jack Lester's throughball to put the Spireites ahead in the 28th minute, before Alan Goodall doubled their lead with a deflected shot after the break.
Magpies strikers Delroy Facey pulled one back with his third goal in as many games and Jamie Clapham tested home keeper Trevor Carson from long range as the visitors looked to level.
Chesterfield sub Paul Harsley made the points safe two minutes from time when he forced the ball home from a tight angle after Russell Hoult had kept out Derek Niven's effort.
Both sides began the local derby brightly and Lester fired just wide of Hoult's left-hand post before Kevin Austin missed another chance for Lee Richardson's men when he nodded a corner inches wide.
But Ward was less wasteful when played in by Lester and he coolly rounded Hoult to give Chesterfield the advantage.
The closest County came to scoring in the first half was a shot from midfielder Richard Butler, which flew just over moments before Ward's strike.
County looked the better side in the opening exchanges of the second half before Goodall appeared to have put the game beyond them in the 58th minute when his 20-yard effort deflected off defender Jamie Clapham past the helpless Hoult.
But Facey gave County hope three minutes later by nodding in Miles Weston's cross and Carson did well to hold two low efforts from outside the box by Clapham.
Harsley sealed Chesterfield's second win of the week with his close-range effort as the clock ticked down.