Stephen Foster notched a late goal to earn the Tykes a precious point in their fight against relegation to League One.
Flitcroft told reporters: "This team (Cardiff) start quick and come at you. We didn't want to be expansive, we tried to be solid.
"This team don't know when to give in. They give us everything every day, they give us the full lot and they gave us that tonight.
"It took too long to go in (the goal), I thought it would never drop in. I'm absolutely over the moon."
Barnsley are 19th in the Championship and are two points clear of the drop zone.