Alex Nicholls put the hosts in front when his shot from 20 yards squirmed under Terriers keeper Alex Smithies.
The visitors turned the game around through a brilliantly taken goal from Kevin Kilbane before Jamie McCombe's back-post header gave them the lead.
Matt Richards's deflected free-kick equalised for Walsall but an overhead kick by Peter Clarke and Jordan Rhodes's strike gave Huddersfield the win.
The result means Huddersfield climb into the League One automatic promotion places after Southampton could only draw with Notts County.
Walsall drop back to the bottom of the table, seven points off safety.
Huddersfield Town manager Lee Clark said: "The last few weeks we haven't been playing at our full potential and the way we'd like to play.
"But what we are doing is winning football matches, which is what it's all about ultimately if we want to achieve what we want to do.
"The lads stuck in and showed good character. When we did show flashes of our potential and passing the ball and getting our wide men and forward players on the ball, we created opportunities."
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