The plaintiff, Brazilian company DIS, had accused Neymar, his father, and the former presidents of Santos and Barcelona of having intentionally hid the cost of his transfer to avoid paying DIS what it was due as the partial holder of his player rights.
However, the court said in a statement on Tuesday that "it has not been proven that there was a false contract or that DIS was intended to be harmed."
The verdict is not a surprise following the decision by Spanish state prosecutors to drop all charges during the trial. That left only the lawyers of DIS to continue arguing their case.
DIS had initially sought a five-year prison sentence for the 30-year-old Neymar. But following the withdrawal of the state prosecutors, DIS' lawyers reduced their demands to two-and-a-half years of prison.
The legal victory for Neymar comes days after he and his Brazil team were eliminated from the World Cup by Croatia on penalties in the quarter-finals.
The other defendants declared innocent were Neymar's father, who goes by the same name, his mother, former Santos president Odilio Rodrigues and former Barcelona executives Sandro Rosell and Josep Bartomeu.
DIS, which owns a chain of supermarkets in Brazil, said it acquired rights in 2009 to receive 40% of a future Neymar transfer when it paid the player's family 5 million Brazilian reals (then $A3m). DIS received €6.8 m ($A10.6m), its due percentage from the €17m ($A26m) that Barcelona and Santos initially announced as the transfer fee between the clubs, but said its cut should have been assessed from what it claimed was the real cost of about €82m ($A128m).
The court said the other monies that Barcelona paid to Neymar's family business, N&N, as well as to Santos in separate contracts, were legal. Those included a €40m ($A62m) payment that Rosell, then Barcelona's president, negotiated with Neymar's father in 2011 to ensure he would later join Barcelona, as well as separate deals between the Spanish club and Santos for a friendly match and the right to first refusal for other Brazilian players.
Neymar joined Barcelona from Brazilian club Santos at the age of 21 amid massive fanfare, when he was already hailed as one of the world's top players. He helped the Spanish giant win a Champions League title and other trophies before he forced a move to current club Paris Saint-Germain in 2017.
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