Striker Matthias Lepiller was 18 when he left Le Havre for Italy. He had trained at the club's academy and had been offered a contract, Le Havre said in a statement.
"After a long procedure, FIFA have just made a ruling recognising the rights of Le Havre and condemning Fiorentina to pay (Le Havre) over 600,000 euros in terms of compensation for schooling and damages", the statement read.
"This is a new step forward towards recognising the rights of clubs involved in schooling," it added.
Le Havre, now in the second division, have accused Manchester United of illegally recruiting one of their players, French midfielder Paul Pogba. Manchester United have denied any wrongdoing.
French clubs are proud of their academies and several have accused foreign clubs of illegally plundering their talent.
Chelsea were banned by FIFA from operating in the next two transfer windows over their signing of French youngster Gael Kakuta from French side Racing Lens.
Lepiller, now 21, failed to make it at Fiorentina and plays for Belgian second division club Eupen.
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