Schlei-Ostsee is an Amt ("collective municipality") in the district of Rendsburg-Eckernförde, in Schleswig-Holstein, Germany. Its seat is in Eckernförde, itself not part of the Amt. It was formed on 1 January 2008 from the former Ämter Schlei, Schwansen and Windeby.

The Amt Schlei-Ostsee consists of the following municipalities:

  1. Altenhof
  2. Barkelsby
  3. Brodersby
  4. Damp
  5. Dörphof
  6. Fleckeby
  7. Gammelby
  8. Goosefeld
  9. Güby
  10. Holzdorf
  1. Hummelfeld
  2. Karby
  3. Kosel
  4. Loose
  5. Rieseby
  6. Thumby
  7. Waabs
  8. Windeby
  9. Winnemark

Coordinates: 54°34′59″N 10°00′00″E / 54.583°N 10.000°E / 54.583; 10.000