Conor Chaplin hit a fine late leveller to rescue a point for Pompey in a scrappy contest at The Hive.
A largely turgid encounter looked to be heading for a goalless scoreline, with few chances to excite those in the stands.
But Mauro Vilhete converted a late free-kick to give the home supporters cause to cheer and deflate the large travelling army.
Substitute Chaplin perked them up in the dying moments, however, with a peach of a shot that left Bees keeper Josh Vickers with no chance.
Paul Cook unsurprisingly stuck with the same side that beat Blackpool earlier in the week – naming an unchanged starting 11 for a fourth successive game.
The first half was a distinctly forgettable affair, with neither outfit being able to find their rhythm in a scrappy encounter.
Barnet won a free-kick 30 yards out, but Ruben Bover’s delivery swung out of play in a moment that summed up the action on offer.
The visitors finally carved out a decent opening on 20 minutes when Kyle Bennett released Gary Roberts down the right and the latter’s cross was glanced narrowly wide by Eoin Doyle.
Then, at the other end, David Forde made a fine reaction save to stop Curtis Weston from volleying home Vilhete’s centre.
And it was the Bees who finished the half looking the stronger side, with the Blues guilty of some sloppy play on the ball.
Former Pompey loannee John Akinde did brilliantly to chest the ball down on 38 minutes and send a shot dipping inches over the crossbar.
Charlie Clough then got on the end of a corner and his header was deflected just past the post by a relieved Michael Doyle.
Half Time: Barnet 0 Pompey 0
Cook made a double switch at the start of the second half, as Bennett and Jamal Lowe were replaced by Chaplin and Danny Rose.
That saw Pompey match their opponents’ 4-4-2 system, with Roberts at the tip of a diamond midfield.
The visiting fans – who made up more than 50 per cent of the total crowd – were making a racket in the stands.
But there was little action of note happening on the pitch, as the second half continued in the same vein as the first.
Chaplin got crowded out after collecting Amine Linganzi’s pass and charging into the box, as chances eluded both sides.
The hosts did go close on 66 minutes after Akinde won a soft free-kick just outside the area and Bover curled it onto the roof of the net.
And the Blues began to show more urgency as the minutes ticked down, with Chaplin having a shot blocked.
They were starting to look the more dangerous side, although it took a fine Christian Burgess challenge to finally halt the rampaging Akinde.
Carl Baker came on for the tiring Roberts for the final 10 minutes as Cook made his last throw of the dice.
But it was Barnet who forged ahead 10 minutes from time when Justin Amaluzor was fouled just outside the box and Vilhete stepped up to curl the free-kick over the wall.
It looked like the hosts were going to hang on for all three points – although CHAPLIN had other ideas.
The substitute had not had much joy since entering the pitch, but found the net with a rocket of a shot from 25 yards that flew into the top corner.
He celebrated with the fans first and then those on the bench, and it proved enough to secure a share of the spoils.
Barnet (4-4-2): Vickers; Clough, Nelson (c), Santos, Johnson; Vilhete, Bover (Sweeney 69), Champion, Weston; Akinola (Amaluzor 75), Akinde
Goals: Vilhete 82
Subs not used: McKenzie-Lyle, Dembele, Taylor, Tutonda, Coulson
Pompey (4-2-3-1): Forde; Evans, Burgess, Clarke, Stevens; Linganzi, M.Doyle (c); Lowe (Rose 46), Roberts (Baker 80), Bennett (Chaplin 46); E.Doyle
Goals: Chaplin 89
Subs not used: O’Brien, T.Davies, Naismith, Hunt
Referee: Mark Brown
Attendance: 4,571 (2,430 Pompey fans)