The former France international had been struggling for playing time at the Parc des Princes, and will spend the rest of the season at the Geoffroy Guichard
The French midfielder had been struggling to secure a first-team place ahead of the likes of Blaise Matuidi and Thiago Motta in Carlo Ancelotti's side, and has been allowed to leave to get more game time.
"The midfielder from Evreux [Bodmer] has been loaned by Paris Saint-Germain to Saint-Etienne until June 30, 2013," a statement on the capital club's website read.
Bodmer arrived at the Parc des Princes from Olympique Lyonnais, and has made 91 appearances for the club, scoring 13 goals.
Saint-Etienne currently sit in sixth place in the Ligue 1 table, 11 points behind first-placed PSG.
The former France international has also represented Caen and Lille.