Striker Tresor Kandol struck a late second half winner to ease Barnet's relegation fears.
Kandol played for Darlington earlier in the season and returned to haunt his old club with a crucial winner ten minutes from time.
After some sustained pressure Kandol rose high from the box to head in Nick Bailey's cross for the only goal of the game.
But Barnet will have to thank keeper Ross Flitney who preserved their lead with a stunning triple save three minutes from time.
With time running out Jamal Johnson saw his left foot shot on the edge of the area pushed away by Flitney and somehow the keeper managed to keep out the follow ups from substitutes Taiwo Atieno and Akpo Sodje.
Former Darlington striker Kandol was a constant thorn in the visitors side and had a goal ruled out in 16 minutes for an offside.
He was then involved 8 minutes before the break when he got on the end of Dean Sinclair's right-wing cross only for the keeper Sam Russell to make a comfortable save.
Eight minutes after the break Russell again denied Kandol before Darlington substitute Atieno blew a golden chance just after the hour. Valentine swung in across from the right, Atieno was completely unmarked six yards out but somehow managed to head wide.
Barnet sub Liam Hatch seized on a mistake by Matt Clarke set up Sinclair who dragged his left foot shot from ten yards wide.
Sinclair was involved in a controversial decision in 71 minutes when he appeared to be wrestled to the ground in the area by Clarke only for the referee to wave away any penalty claims.
Barnet finally made their pressure count on 80 minutes when Kandol headed in Bailey's cross before Flitney's heroics earned the win.
