The Kochelsee Railway (German: Kochelseebahn, literally "Lake Kochel Railway") is a branch line in Upper Bavaria (Oberbayern), Germany, that is just under 36 km long, single-tracked and fully electrified.

The route was electrified on 4 March 1925 and is currently (2006) worked by electric multiples of the DBAG Class 425/426.

Apart from a few exceptions in the morning commuter services the trains run hourly, with a crossing in Bichl shortly before the half-hour and good connections in Tutzing in both directions.

The commuter services run straight through to and from Munich Hauptbahnhof (main station), the crossing then usually takes place in Seeshaupt due to the change in frequency.

Such trains, headed northward to Munich may often be coupled with services reaching Tutzing via a more western line, servicing destinations as far south as Innsbruck (in Tyrol, Austria), Mittenwald or Garmisch.