The ex-Belgium Under-21 international spent two spells on loan to the Saddlers from Stoke City back in 2012.
Cuvelier, 23, was a free agent following his release from Sheffield United at the end of last season.
He follows fellow midfielders Erhun Oztumer and Kacy Milan Butterfield as the third summer signing made by new Walsall manager Jon Whitney.
"I've worked with Jon Whitney before and I've played with Dean Holden," he said.
"They have seen me play at my very best. I'm hungrier than ever to have a successful season and I am so happy to be here again. This is a club I love."
After spending his youth career in his native Belgium with Excelsior Bievene, Le Louviere and Mouscron, Cuvelier first came to England with Portsmouth in 2008.
"I am really excited about helping Flo fulfil his potential," added Whitney.
"He became a fans' favourite due to his wholehearted and committed performances. We both agreed that Walsall was the best option for him due to our football philosophy and Flo's previous loan periods with the club."
Cuvelier's arrival came on the same day that Walsall announced the full scale of player departures at Bescot, with Romaine Sawyers, Jason Demetriou, Paul Downing and Milan Lalkovic having all turned down new deals.
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Walsall have re-signed sign former loan midfielder Florent Cuvelier for the third time on a one-year contract.