Radolfzell am Bodensee (German pronunciation: [ˌʁaːdɔlfˈtsɛl ʔam ˈboːdn̩zeː], lit. 'Radolfzell on the Lake Constance') is a town in the state of Baden-Württemberg, Germany, located at the western end (Zeller Lake) of Lake Constance, approximately 18 km (11 mi) northwest of the city of Konstanz (Constance). It is the third largest town, after Konstanz and Singen, in the district of Konstanz.

It is situated in the Hegau region. The mouth of the river Radolfzeller Aach is located west of Radolfzell.

It is a well-known health care town (Mettnau-Kur). In 1990, Radolfzell was named the Federal Environment Capital City of Germany.

This town developed out of a monastery founded in 826 AD as a "cell" under Bishop Radolf of Verona. The town belonged to the Abbey of Reichenau, then for a long time to the House of Habsburg, and for 40 years it was a Free Imperial City.

In the centre is the Gothic Cathedral Unserer lieben Frau (lit. 'Of our Dear Lady'), dating from the 15th century and decorated in the Baroque style in the 18th. One particularly beautiful feature is the Rosary altar by the Zürn brothers and the Master of the House's Altar (1750) which contains the relics of the local Radolfzell saints Theopont, Senesius and Zeno. The Hausherrenfest is celebrated in their honour every year on the third Sunday in July, and the next day a famous Water Procession is held, as it has been every year since 1797. The citizens of the nearby village of Moos make a pilgrimage to Radolfzell in picturesquely decorated boats to fulfil an ancient oath.

A notable structure in the town is the Austrian mansion in the market square, built in stages from the 17th to the 19th century, the knightly hall dating from 1626. Also of note are a number of historical Patrician houses.

Radolfzell was the birthplace of cartographer Martin Waldseemüller's mother.

(Lord Mayor^{[further explanation needed]} since 1975)