The home side went in front through Jamie Ward but a Tommy Wright equaliser earned Darlington the point they required.
The odds had been stacked heavily against the visitors who had six strikers missing and only Wright available to play in attack.
Quakers manager Dave Penney put out a formation designed to frustrate Chesterfield and the ploy worked during a scrappy and untidy first half which was low on goalmouth action.
But Darlington were forced into a change of tactics when Chesterfield took the lead five minutes into the second half.
A long ball down the left was headed on by Steve Fletcher and Ward found enough space inside the penalty area to fire a low shot across the goalkeeper and inside the far post.
Darlington had to come out and play and, to their credit, they responded impressively and for the first time in the match began to examine the home defence.
Jason Kennedy shot straight at Barry Roche in the 58th minute but Wright did even better ten minutes later.
Again the goal came out of nowhere with a long ball played down the left which Neil Wainwright flicked on. Wright took the ball down on his chest and showed good composure to guide a low shot past the outstretched hand of Roche and inside his left-hand post.
It was the striker's 15th goal of the season but only his second in 13 matches and it proved to be a priceless one for his team.
From then on, Chesterfield had to throw caution to the wind and they brought on top-scorer Jack Lester who had been out for nearly a month with a broken nose.
They threw everything at Darlington but Lester was frustrated as Chesterfield's pressure resulted in few clear chances.
There was a late scare for the visitors when the Spireites forced two corners in stoppage time but they held on and the players celebrated at the final whistle and will now have the chance to get the promotion that at one stage they appeared to be on course to achieve automatically.