Defender Ian Hendon scored two second- half penalties as relegation-haunted Barnet came from behind to win.
After twice almost going behind, County took the lead when Steve Scoffham was released down the right by David Pipe and slotted the ball into the net.
Ben Strevens had a goal ruled out before Barnet levelled from the spot through Hendon on 63 minutes.
And Hendon won it from the spot after Mike Edwards had fouled Andy Hessenthaler in the penalty box.
Barnet: Flitney, Hendon, Charles, Clist, Warhurst, Bailey, Strevens, Fuller, Vernazza, Hessenthaler (Sinclair 79), Kandol.
Subs Not Used: Reed, Batt, Roache, Gross.
Booked: Kandol.
Goals: Hendon 64 pen, 72 pen.
Notts County: Pilkington, Pipe, Edwards, Baudet, Doyle, Palmer, Crooks, Scoffham, Ullathorne, Needham (Long 82), Chillingworth (White 70).
Subs Not Used: McMahon, Martin, Marshall.
Booked: Crooks.
Goals: Scoffham 46.
Att: 2,841
Ref: J Moss (West Yorkshire).