The 24-year-old – who had been subject of interest from Wolves earlier in the summer – is set to fly into Birmingham for a medical today, according to reports in the south of France.
Villa moved in to agree a deal which could rise to around £30m, if all conditions and add-ons are met.
Guessand has been likened in style to Didier Drogba and was the second-highest rated forward in France’s Ligue Un last year behind Paris St-Germain’s Ousmane Dembele.
He had been heavily linked with a move to Crystal Palace in recent days but Villa swooped in and look set to seal the deal today.
Guessand will become Villa’s second senior signing of the summer – after goalkeeper Marco Bizot from Brest – and the first to involve a fee amid Villa’s ongoing efforts to meet profit and sustainability rules.