A fourth minute strike from Gavin Hoyte was enough to seal victory for Barnet, despite the Bees playing with ten men for much of the second half.
Hoyte connected with a Sam Togwell long throw to put Barnet ahead, before Andy Yiadom saw red with just over half an hour left on the clock.
But Martin Allen’s side held on to claim all three points at The Hive.
The Bees took the lead with the first chance of the game.
John Akinde charged down the right in the third minute only to see his low cross cleared away – Hoyte connected with the resulting Togwell throw-in to give Barnet the lead.
Rovers pushed to get back into the game, and Lee Mansell headed a right wing cross over the bar on 12 minutes.
A short corner allowed Daniel Leadbitter to cross from the right after 39 minutes, but Ellis Harrison’s bullet header flew wide of Jamie Stephens’ left-hand post.
The first half of the match was short on clear-cut chances, but the second began with a good effort from the visitors – Stephens getting down to stop Harrison’s 46th minute shot from the left of the box.
The Bees found themselves down to ten men when Andy Yiadom received a harsh looking red card in the 57th minute.
Yiadom slid in hard on Stuart Sinclair, but looked to win the ball in the process.
The Pirates pressed for an equaliser and substitute Liam Lawrence fired a shot narrowly over the bar on 70 minutes.
Stephens then saved well from Jermaine Easter in the 89th minute, after the forward lashed a left sided shot at the keeper.
But the visitors struggled to create many clear chances in the latter stages of the match, and the Bees defended doggedly to claim a valuable win.
Next up for Barnet is a home clash with Carlisle United.
BARNET: Stephens, Hoyte, Johnson, Dembele, N’Gala, Yiadom ©, Weston, Togwell, Gambin, Akinde (Batt 80’), McLean (Champion 63’).
Subs Not Used: McKenzie-Lyle, Odoffin, Taylor, Stevens, Gash.