Goals from Ben Whiteman and Shaquile Coulthirst, either side of the break, extended the Stags unbeaten run on the road to four games - and unbeaten league run to seven.
Manager Steve Evans named an unchanged line-up, for the third league game in a row, at the Hive after last week’s win over Leyton Orient.
Mansfield mounted numerous attacks early on, but the Bees’ backline held firm to deny any clear-cut chances.
In the 22nd minute Whiteman’s cross cannoned off the post with Coulthirst’s rebound well saved by Josh Vickers.
Vickers had to receive treatment after injuring himself during the save.
On the half hour mark the Stags continued to pepper the hosts’ goal.
Krystian Pearce’s glancing goal-bound header was punched away by Vickers.
Down the other end, Jake Kean - who has conceded just twice since joining the Stags on loan from Sheffield Wednesday - brilliantly denied Jamal Campbell-Ryce.
With nine minutes left before the break, the Stags struck through Whiteman’s third goal in five games.
The youngster, who joined in January, slotted home from inside the box after being played in by Coulthirst.
Just before the hour the Stags were awarded a penalty.
Coulthirst was hauled to the ground by Ricardo Santos on the right-hand of the box.
And Peterborough United loanee Coulthirst stepped up to dispatch his sixth goal of the season by hitting the spot kick down the middle.
Substitute Ruben Bover almost pulled one back for the Bees as he curling free-kick crashed against the post, before the Stags scrambled to clear the danger.
First goalscorer Whiteman almost turned provider as he set Alfie Potter on his way, only for the latter to be superbly thwarted by Vickers late on.
Deadline day signing Alex MacDonald came off the bench to make his debut with a few minutes left.
Barnet: Vickers, Clough, Almeida Santos (Coulson, 73), Nelson, Johnson, Vilhete, Champion (Bover, 45), Weston, Kyei, Campbell-Ryce (Mason-Clark, 45), Akinde.
Unused subs: McKenzie-Lyle, Dembele, Sweeney, Taylor.
Mansfield: Kean, White, Pearce, Bennett, Benning, Collins, Whiteman, Byrom (MacDonald, 88), Hamilton, Coulthirst (Potter, 77), Rose (Green, 68).
Unused subs: Shearer, Arquin, McGuire, Baxendale.
Referee: Lee Collins (Surrey)
Attendance: 1,859 (391)