Millstatt am See is a market town of the Spittal an der Drau District in Carinthia, Austria. The traditional health resort and spa town on Lake Millstatt is known for former Benedictine Millstatt Abbey, founded about 1070.

It is situated on the southern slope of the Gurktal Alps (Nock Mountains), on an alluvial fan peninsula on the lake's northern shore. The municipal area reaches from an elevation of 588 m (1,929 ft) at the lakeside to 2,101 m (6,893 ft) AA at the crest of the Millstätter Alpe massif. It comprises the cadastral communities of Millstatt proper, Obermillstatt, Matzelsdorf, and Laubendorf.

Beneath the Millstatt marketplace stand the extensive buildings of the former Benedictine monastery with its four massive towers and the monastery church at the highest point.

While the oldest archaeological artifacts found in the area date back to the Neolithic, the name "Millstatt" may refer to the Celtic expression "mils" meaning mountain stream or brook. The Celts entered this region from the 5th century BC onwards, their kingdom Noricum came under control of the Roman Empire in 16 BC. During the Migration Period in the 6th century Slavic tribes settled here in the principality of Carantania, which became a march of Bavaria and the Frankish Empire in the late 8th century. According to legend, a Carantanian duke Domitian converted to Christianity and built the first church of Millstatt. He also had one thousand statues of pagan gods ("mille statuae", see the coat of arms) gathered and thrown into the lake.

A first guest from Vienna is documented in 1869, arriving by train at the Villach railway terminus and staying at the local inn. From about 1870 onwards Millstatt developed from a sedate village to a fashionable summer resort for the nobility and the wealthy bourgeoisie of the Austro-Hungarian Empire. It was in this year when wealthy publisher and son of an old Bohemian glass manufacturing dynasty, Rudolf Schürer von Waldheim, came to Millstatt to build the first hotel in town, the Hotel See-Villa according to plans designed by architect Karl Mayreder in 1883-84. The area gained direct access to the Austrian Southern Railway line by the opening of the branch-off to nearby Spittal-Millstättersee station in 1873, followed by the inauguration of the Tauern Railway line in 1909.

On 7 June 1885, Archduke Karl Ludwig of Austria, younger brother of Emperor Franz Joseph, visited the See-Villa and talked about it in highest tones; thus, increasing the popularity of the hotel and of Millstatt in general. During the Fin de siècle era of the 1880s and 90s numerous inns and hotels opened, while nobles and rich citizens had lavish holiday homes erected on the lakeside. The town's increasing economic dependence on tourism became obvious in the first recession during World War I, later Millstatt was badly hurt by the Great Depression of the late 1920s. The local authorities tried to encounter the narrow circumstances by obtaining spa town status in 1921, laying out a promenade and spa gardens, and the opening of the public lido with its prominent diving tower in 1931.

However, conditions worsened with economic sanctions applied by the German government on the First Austrian Republic from 1933. In addition, the political turmoil during the rise of Austrofascism and the transition to the Federal State of Austria erupted in violent fights, when during the 1934 July Putsch local Nazis attacked the Millstatt police station. Tourism was definitely disrupted in World War II, while several Kinderlandverschickung camps were established, mainly for children from Berlin.

After the war many villas were requisitioned by the British occupation forces. Nevertheless, in the 1950s and 60s, Millstatt became a popular destination of Wirtschaftswunder mass tourism, mainly from West Germany. The number of overnight stays in summer reached heady heights, largely affecting the biological diversity and ecology of the lake. The increasing eutrophication could be stemmed by sewage works, but also due to a declining number of guests, which has reached the climax around 1980. In recent years Millstatt has become the site of numerous vacation properties.