The Saddlers recovered from last week's home hammering at the hands of Oldham with a battling display.
In defence they completely bottled up the home attack and, when he was needed, keeper Clayton Ince made some tremendous saves.
In midfield they worked hard and covered everything to stop Hartlepool getting into their stride and they got their reward with a last-minute winner.
In defence Anthony Gerrard and Scott Dann kept the shackles on Richie Barker, while in midfield newcomer Dwayne Mattis, on loan from Barnsley, helped to stop Hartlepool playmakers Gary Liddle and Willie Boland taking command of the game.
In a drab first half in which Walsall showed that they meant business, they managed to limit the home attack to just two chances.
Ince saved well from Richie Humphreys, while Andy Monkhouse blasted a volley wide.
After the break, Ince did even better as he somehow saved a Barker header after James Brown's right-wing cross and did just as well to stop a Liddle shot that looked a certain goal.
But Hartlepool never looked like hitting their stride, and as the game into its last minute, the latest of many long clearances from the Walsall penalty area was flicked on by Tommy Mooney and substitute Paul Hall danced through the defence before slotting his low shot into the bottom corner for an unlikely winner.