The court ruled that the France and Marseille midfielder's claims for "retraining compensation, notice pay and (...) paid holidays" were admissible, according to the judgement handed down on Thursday and consulted by AFP.
Rabiot (30), who had not extended his contract with PSG, was let go by his parent club in December 2018 and did not play again until the end of the season. The player left PSG in June 2019 to join Juventus.
"It's an important decision because it sanctions the club for the arbitrary and unjustified marginalisation of the player," his lawyer Romuald Palao told AFP.
"Furthermore, at the time, he was unduly penalised by the club, a sanction that should not have existed," added the lawyer.
According to a source close to the club, this decision "is not a victory" for Adrien Rabiot, since he only got "10 per cent of what he was asking for: three months' salary in redundancy pay due to the reclassification of his fixed-term contract into an open-ended contract".
"However, this is a very questionable decision from a legal point of view, in many respects, and we will certainly challenge it," added the source, who said that the club is "suffering the legal consequences of the unstable legislative system prior to 2015", which did not provide security for contracts in professional sport, according to the source.
By asking for his nine-year fixed-term contracts (CDD) with PSG to be converted into open-ended contracts, "Adrien Rabiot has merely asserted his rights. His request is based on solid legal arguments," added his lawyer, Me Palao.
"Adrien's reaction is also well-founded because, at the time, he was arbitrarily denied the opportunity to play football, his great passion," he concluded.
Rabiot joined PSG in 2010, aged 15, and became a first-team regular and an international in 2016.
"Adrien would not have submitted this request for requalification if everything had gone well at PSG," the player's entourage explained. "He launched this procedure because he was left out of the team and had to endure very unpleasant moments for seven months."
Both parties have two months to lodge an appeal.
PSG had no comment when contacted by AFP.