Portorož (pronounced [pɔɾtɔˈɾóːʃ] ^ⓘ; Italian: Portorose) is a Slovenian Adriatic seaside resort and spa settlement located in the Municipality of Piran in southwestern Slovenia. Its modern development began in the late 19th century with the vogue for the first health resorts. In the early 20th century Portorož became one of the grandest seaside resorts in the Adriatic, along with Opatija, Lido and Grado, then as part of the Austrian Littoral. It is now one of Slovenia's major tourist areas. Located in the centre is the Palace Hotel, once one of the most important resorts for the Austro-Hungarian monarchy, and currently one of the finest hotels between Venice and Dubrovnik.

The settlement and its surrounding areas are served by Portorož International Airport which is located in the nearby village of Sečovlje.

The Slovene name Portorož is borrowed from Italian Portorose, literally 'port of roses', which was recorded in the 12th century as Porto di rose. The name is derived from Santa Maria delle Rose 'St. Mary of the Roses', the patron saint of a former church in the settlement.

The history of the settlement is directly connected to that of the neighbouring town of Piran, with Illyrian settlers already living there in the prehistoric era. They were followed by Celtic tribes, which were later conquered and annexed by the Roman Empire in 178 B.C. Archaeological finds suggest that in this period many farms and villas, also named villae rusticae, were built in the area. A large development of the area followed only after the demise of the empire, with enlargement of the number of settlers seeking shelter from attacks by the Barbarians.

In the 7th century, the area was a part of the Byzantine Empire. Due to increasing dissatisfaction with the feudal rule, as well as the rising power of the Venetian Republic, the settlement of Pirano signed a trade treaty with Venice, which included a lesser degree of autonomy.

One of the first religious orders who came to this area was the Benedictines. In the 12th century, the broader region already had four monasteries and even more churches. Among those, one of the oldest was the church of Our Lady of the Rosary, which stood by the bay in the beginnings of the 13th century. Its name was Sancta Maria Roxe or S. Maria delle Rose, and in 1251 the bay was named by it Portus sanctae Mariae de Rosa.

One of the most important roles in the history of the settlement was the monastery of Saint Laurence, where the Benedictines healed rheumatic illnesses, ascites and other diseases with concentrated saltwater and saline mud. In 1210, the area was overtaken by the Patriarchy of Aquileia.

In the 13th century, Pirano entered a brief war from December 1282 to January 1283, in which it was defeated by the Venetian Republic.