Mittersill lies approximately 25 km to the west of Zell am See, 30 km to the south of Kitzbühel and 27 km east of the start of the Salzach Valley in Krimml.
Mittersill straddles the Salzach River and one of its tributaries; the Felber. The town is bordered to the south by the Hohe Tauern mountain range, and to the north by the Kitzbühel Alps.
It has traffic links running east to west and north to south. The Felbertauern road tunnel runs south through the Hohe Tauern at an elevation of about 1630 m, providing a connection with Lienz in East Tyrol. To the north lies the Thurn Pass at an elevation of 1274 m, providing a connection with Kitzbühel and Tyrol.