The Saddlers completed the double over Bournemouth despite having striker Febian Brandy sent off for a second bookable offence in the 73rd minute.
Walsall took the lead after 27 minutes when Sam Mantom, the former West Brom midfielder, hammered in a 25-yard cross-shot which beat goalkeeper David James in the crowded goalmouth.
The visitors were almost level 12 minutes later when Josh McQuoid crossed for Brett Pitman to plant a header against the crossbar with keeper Ian McLoughlin beaten.
They paid for that miss when, in stoppage time at the end of the first half, Will Grigg was brought down by James, who was only shown a yellow card, and Grigg hammered home a low penalty for his ninth goal of the season to give Walsall a two-goal cushion.
Bournemouth pulled a goal back in the 49th minute when Pitman headed in Lewis Grabban's cross and Wes Thomas headed against the bar as the Cherries chased an equaliser.
But a mistake by Eunan O'Kane, who picked the ball up in the penalty box after mistakenly thinking Walsall had been awarded a free-kick, proved decisive. Grigg hammered in his second goal of the afternoon from the resulting spot-kick after 79 minutes.