Lawyers for Mbappe said they noted the decision “with satisfaction”.
“It re-establishes a simple truth – even in the professional football industry, labour laws apply to everyone.”
PSG said the club “reserved the right to appeal”.
“Paris Saint-Germain acknowledges the judgment handed down by the Paris labour court, which it will comply with.
“PSG has always acted in good faith and with integrity.”
The French club had said they were basing the €440m figure they were claiming in part on an aborted €300m transfer to Saudi club Al Hilal which Mbappe refused in June 2023.
Mbappe left for Real Madrid on a free transfer when his contract expired the following summer.
He insisted he made no agreement in 2023 to waive any payment from the club.
Mbappe initially filed a complaint in June over the way he was treated by PSG at the start of the 2023-24 season.
Mbappe argues that he was sidelined by PSG and made to train with players the club were trying to offload after refusing to agree to a new contract.
It is a widespread practice that in France prompted the players’ union to lodge a complaint last year.
Mbappe was not invited to take part in PSG’s 2023 pre-season tour of Asia and missed the first game of that season but was later recalled to the team after holding talks with the club.
After seven seasons with PSG, he joined Real Madrid where he earns a reported annual salary of €30m.
Mbappe scored 256 goals in 308 games for PSG but the club won the Champions League for the first time last season following his departure.
