The Frenchman was recently released by the Ligue 1 champions after falling down the pecking order at the Parc des Princes.
PSG have thanked Bodmer for his contribution in the French capital following his move to the Allianz Riviera.
A statement on PSG's official website read: "Paris Saint-Germain and Mathieu Bodmer decided to end their collaboration on Monday. The player is now free to sign with OGC Nice.
"The club would like to thank Mathieu Bodmer for his professionalism throughout his time in the capital and wish him good luck for the rest of his sporting career."
Bodmer spent the second half of last season on loan at Saint-Etienne.