It looked like Chesterfield would deservedly take all the points back home following Akwasi Asante’s cool 80th minute penalty.
But they failed to deal with a Josh Rees corner with two minutes to go as sub Adrian Clifton powerfully headed home.
It leaves Chesterfield trailing County by four points and having played two games more.
Although it was always going to be a tough test against their fellow promotion rivals - boasting the best defence in the league - Spireites will see this as more than a missed opportunity.
Spireites dominated the first 45 minutes with some slick passing and high energy football pushing The Wood onto the back foot.
But too often Paul Cook’s men squandered decent positions and failed to test Taye Ashby-Hammond enough after choosing the wrong final.
The visitors were unable to find the same performance levels after the break as Borehamwood came out with more fight.
But it was a cruel finale for Paul Cook’s men, who though lacking the same spark of the first half, did enough to warrant the win.
Spireites made two changes from the side which drew 2-2 with Southend last time out, with Joe Quigley and Saidou Khan coming into the starting eleven.
Borehamwood included former Spireites Will Evans and Scott Boden.
Jim Kellermann miscued a long range effort on five minutes after a positive start from Spireites.
Alex Whittle’s deep cross was just too high for Joe Quigley as the visitors continued to dictate the play.
Calvin Miller saw a shot blocked after Saidou Khan played him in before Boden blazed over.
Tom Whelan failed to hit the target from a great position as Chesterfield’s dominance increased.
Josh Rees looped a header onto the roof of the net, before Tyrone Marsh had a shot blocked for a corner.
Whelan curled a comfortable shot at Ashby-Hammond after an excellent turn by Khan in midfield kick-started a counter-attack.
Boden became the third Borehamwood player to pick up a booking inside the opening half hour for a late tug on Whittle.
Josh Rees fired inches wide after a surging run five minutes into the half.
David Stephens wasn’t far away a minute as the hosts showed new purpose.
Whelan had a shot blocked for a corner on the hour mark as Chesterfield looked to have weathered the storm.
Loach pulled off a brilliant diving save to keep out Rees on 72 minutes
Chesterfield were given a life-line with ten minutes to go when Jacob Mendy Mendy was ruled to have handled a cross in the box.
And Akwasi Asante kept his cool from the spot to send the keeper the wrong way after a little shimmy.
But Chesterfield switched off with just three minutes to go as Clifton levelled from a Rees corner.
Borehamwood: Ashby-Hammond, Evans, Stephens, Rees, Boden (Orsi 65), Marsh, Raymond (Clifton 84), Fyfield, Lewis, Mendy Mendy, Smith (Mafuta 60).
Subs not used: Comley, Ranger, Orsi.
Chesterfield: Loach, Grimes, Kellermann, Maguire, Whitte, Mandeville, King, Khan, Whelan (Asante 74), Miller, Quigley.
Ref: Matthew Rusell.
Att: 1621 (570)