The Belgian has made three appearances since joining in January, scoring once, and Saddlers boss Dean Smith could not hide his delight after sealing the deal with the Potters.
"I'm really pleased that Flo is staying here," he told Walsall's official website.
"He's made a real impact since he has been here. I'd seen him a lot for Stoke's reserves so I knew what he was all about but, to be fair, for someone who has never made a senior appearance before coming here, he has slotted in like a dream."