Gaienhofen () is a municipality in the district of Konstanz in Baden-Württemberg in Germany. It is located at the border with Switzerland.
Since 1974, Gaienhofen consists of four villages: Gaienhofen, Gundholzen, Hemmenhofen and Horn. Attractions, apart from the Lake of Constance, include the Hermann-Hesse-Höri-Museum and the Museum Haus Dix.
It is home to one or more prehistoric pile-dwelling (or stilt house) settlements that are part of the Prehistoric Pile dwellings around the Alps UNESCO World Heritage Site.
Gaienhofen is twinned with:
There are two landing stages, Gaienhofen and Hemmenhofen. Between spring and autumn, the URh offers regular boat services on the High Rhine and Untersee between Schaffhausen and Kreuzlingen, via Konstanz.