Tresor Kandol scored the only goal of the game to give relegation-threatened Barnet a boost.
Kandol thought he had given his side the lead early in the match, but his header ruled out for offside.
Darlington substitute Taiwo Atieno then sent a header wide, before Barnet's Dean Sinclair missed with his shot.
With 10 minutes remaining Nicky Bailey's cross found the head of Kandol and the striker finished into the far corner of the Darlington goal.
Barnet: Flitney, Fuller, King (Vernazza 67), Charles, Sinclair, Clist, Hessenthaler (Warhurst 77), Yakubu, Bailey, Lee (Hatch 62), Kandol.
Subs Not Used: Reed, Strevens.
Booked: Lee, King, Sinclair, Yakubu, Flitney.
Goals: Kandol 80.
Darlington: Russell, Valentine, Appleby (Peacock 83), Clarke, Martis, Kendrick, Wainwright (Atieno 51), Dickman, Simon Johnson, Cooke (Sodje 68), Jemal Johnson.
Subs Not Used: Norton, Beaumont.
Booked: Jemal Johnson.
Att: 2,845
Ref: R Lee (Brentwood).