Goals from MacDonald, Atkinson and Rose gave the Stags a comfortable lead, Simeon Akinola’s late strike was little more than a consolation for the Bees.
Both sides could have seen penalties awarded in the opening 15 minutes in what was a scrappy affair.
Mansfield, who came into this match 8 unbeaten, stepped up a gear, MacDonald striking the post and Hemmings forcing a save from Ross.
The Stags took the lead shortly the break, neat build up play from Byrom and Benning ended with a ball to MacDonald who beautifully curled the ball in off the far post.
Into the second half and MacDonald missed a golden chance to double his and Mansfield's tally from close range.
10 minutes after the restart, Byrom's corner was headed towards goal by Hemmings and poked home by Atkinson.
Another chance came and went for Mansfield, Hemmings heading wide from infront of goal, Danny Rose made it 3-0 with a good finish.
Substitute Simeon Akinola made the most of a defensive error to pull a goal back.
The Bees put pressure on the Mansfield goal in stoppage time, but it was too little too late.
BARNET: Ross, Brindley, Clough, Santos, Watson, Weston (Nicholson 75'), Akinde, Coulthirst (Akinola 59'), Tutonda, Bover, Nicholls (J. Taylor 79').
Unused subs: Legg, Vilhete, Sule, Plavotic.
Attendance: 3795 (79 Barnet fans)