Mansfield had the edge in a tight first half before Ryan Tafazolli headed them in front on 47 minutes.
Two minutes later Jack Thomas smashed home a second and the home side were beaten and have now not won in four games.
Jack Thomas gave his best display of the season yet, but the back four were also magnificent on a night of many top drawer performances.
Mansfield made three changes. Mitch Rose is serving a one-game ban while Lee Collins and Nathan Thomas are left out from the side that drew 1-1 with Plymouth Argyle on Saturday.
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Into midfield came Jamie McGuire and Reggie Lambe while skipper Nicky Hunt returned to his right back slot after a one-game suspension.
Chris Beardsley returned from a shin injury to be on the Mansfield bench at his former club.
Stags almost made the perfect start as Lambe turned his man on the left wing and got in a low cross that the home side failed to clear, the ball falling for Green, who sliced wide.
But on two minutes it was the home side who almost repeated their feat of an early lead from last season as Conlon powered in a header from a right wing Henry cross, forcing Jensen into a magnificent late tip-over.
On 15 minutes Pearce battled superbly with Williams, driving him to the touchline before robbing him, beating him and clearing, the Stevenage man, clearly annoyed at losing it, diving into a late tackle and lucky to only see a yellow card.
On 28 minutes McGuire was lucky not to be booked too as he slid into a challenge on Hitchcock, his studs going into the Stevenage man’s chest and sparking a pushing contest.
Mansfield were enjoying the lion’s share of possession, but chances were few,
Five minutes from the break Jack Thomas got down the right and tried to thunder a shot past Fulham loanee Joronen at his near post, the keeper conceding a corner.
Two minutes later Westcarr also tested Joronen from 20 yards, the Finnish keeper turning it away for another corner.
This was much better from the visitors and a minute later it took two superb blocks from defenders throwing themselves in the way of the ball in the box to stop Lambe and Benning finishes, Benning then too high with his follow-up as the ball ran back to him.
However, as the game entered two minutes of stoppage time, Stevenage might have stolen the lead themselves.
Breaking quickly, Whelpdale took a long crossfield pass in his stride on the right and cut inside Benning before firing in a low shot that Tafazoli blocked just in front of Jensen.
The home fans decided to boo their side off on the whistle.
Smith replaced Jebb for the start of the second half.
But it was Mansfield who drew first blood inside two minutes.
Chapman floated in a corner from the left and Tafazolli rose to power home a firm header inside the right post for his third goal of the season.
On 49 minutes it was 2-0 at Stags caught the home side napping with a quickly-taken free kick by Benning from deep on the left.
It sent Westcarr through but he chose not to shoot, drawing the keeper before squaring a low pass just when it seemed to moment was gone and Jack Thomas was there to his right to thunder in a finish from 12 yards.
Smith tried to reply for the home side from outside the box two minutes later, the ball flying not too far wide.
Chapman then went into the book on 54 minutes for time wasting at a free kick as Stags tried to kill the game a little.
On 61 minutes tempers again flared as Hitchcock caught Hunt very late, leaving the Stags skipper on the floor in agony.
Hitchcock was booked for the foul as was Lambe for a retaliatory push.
Jack Thomas showed great persistence on the right to win the ball back and cross, Green helping it on and Benning rifling a low shot across goal.
Pearce was then added to the book on 66 minutes for putting his hands up to stop a quick throw being taken. The subsequent free kick was too long and high and had home fans again booing their side’s failings.
There were more boos for Sheringham as he made his final change on 73 minutes, sending on Akinyeli for Conlon.
It should have been all over on 77 minutes as Hughes allowed the ball to bounce off and put Green in one on one with Joronen.
But the usually deadly striker failed to net as the keeper spread himself well and got his body in the way.
With five minutes to go Akinyemi had a shot blocked from a tight angle on the right and then sent a follow-up through a crowd of players and wide of the far post for the increasingly desperate home side.
Green was booked on 87 minutes for rounding the keeper and netting after an offside whistle.
A minute from time Stags sent on Collins for Westcarr as an extra defender and a minute into the added five Beardsley replaced Green, coming on to a warm welcome from his old fans.
It was all they had left to cheer as Stags saw out the remaining minutes without drama for an excellent win.
STEVENAGE: Joronen, McCombe, Hughes, Whelpdale (Kennedy 60), Schumacher, Williams, Hitchcock, Jebb (Smith HT), Henry, Johnson, Conlon (Akinyemi 73). Subs not used: Day, Franks, Pett, Wells. STAGS: Jensen, Hunt, Pearce, Tafazolli, Benning, Chapman, Lambe, McGuire, Jack Thomas, Westcarr (Collins 89), Green (Beardsley 90+1). Subs not used: Shearer, Marsden, Nathan Thomas, Blair, Yussuf. REFEREE: Trevor Kettle of Rutland.
ATTENDANCE: 2,509 (163 away). CHAD STAGS MAN OF THE MATCH: Jack Thomas.