The Port of Rijeka is a seaport in Rijeka, Croatia, located on the shore of the Kvarner Gulf in the Adriatic Sea. The first records of the port date to 1281. It was the main port of the Kingdom of Hungary in the 19th century and the beginning of the 20th century, of Yugoslavia between World War II and 1991, and of Croatia after its independence. Today, it is the largest port in Croatia with a cargo throughput of 13.6 million tonnes (2020), mostly oil, general cargo and bulk cargo, and 344,091 Twenty-foot equivalent units (TEUs).

Rijeka, also known as Fiume, is the principal seaport and the third-largest city in Croatia. It is located in Primorje-Gorski Kotar County on Kvarner Bay, an inlet of the Adriatic Sea and in 2021 had a population of 108,622 inhabitants. Historically, because of its strategic position and its excellent deep-water port, the city was fiercely contested, especially between the Holy Roman Empire, Italy and Croatia, changing rulers and demographics many times over centuries. According to the 2011 census data, the majority of its citizens are Croats, along with small numbers of Serbs, Bosniaks and Italians.