Amt Großer Plöner See is an Amt ("collective municipality") in the districts of Plön and Ostholstein in Schleswig-Holstein, Germany. It is situated around Plön, which is the seat of the Amt, but not part of it. The Amt is named after the lake Großer Plöner See.

It is the first amt in Germany that joins municipalities in different districts.

The Amt Großer Plöner See consists of the following municipalities:

1. Ascheberg
2. Bosau (Ostholstein district)
3. Bösdorf
4. Dersau
5. Dörnick
6. Grebin
7. Kalübbe
8. Lebrade
9. Nehmten
10. Rantzau
11. Rathjensdorf
12. Wittmoldt