Katerini (Greek: Κατερίνη, Kateríni, pronounced [kateˈrini]) is a city and municipality in northern Greece, the capital city of Regional Unit of Pieria in Central Macedonia, Greece. It lies on the Pierian plain, between Mount Olympus and the Thermaikos Gulf, at an altitude of 14 m. The municipality of Katerini has a population of 82,892 (according to the 2021 census). It is the second most populous urban area in the region of Macedonia after Thessaloniki. The close distance between the two cities (68 km), has been beneficial for Katerini's development over recent years. Katerini is accessible from the A1/E75 Athens–Thessaloniki motorway (with the Katerini's South, East and North interchanges) and the A2 motorway to the north. It is served by Intercity, Proastiakos (suburban train) and local trains on the main Athens-Thessaloniki railway line and there is a comprehensive regional and national bus service with its hub in the city.

A popular tourist destination in northern Greece, Katerini is close to the sea (7 km) and to several archaeological sites of great interest such as the ancient city of Dion (5th century BC, 17 km away), ancient Leivithra (27 km away), ancient Pydna (16 km away) and the Castle of Platamon. The beaches of Kallithea, Korinos, Olympiaki Akti (or Katerinoskala), Paralia (where the 3rd Port Authority Department of Skala Katerini is located), Peristasi are visited by both Greek and foreign tourists during the summer season. The base of Mount Olympus and the town of Litochoro, are at a distance of around 20 km from the center of Katerini. The ski center of Elatochori in Mount Pieria is at a distance of 33.4 km from the city's center.

The origin of the name is obscure. Since the 13th century, travellers as well as maps record the existence of a settlement called Hatera (Ἅτηρα), which may have been the origin of the modern name. Thus Felix Beaujour recorded its name as "Katheri", while François Pouqueville gives the name of the settlement as "Kateri Hatera". According to another theory, the city derives its name from the small chapel dedicated to Saint Catherine (Greek: Αγία Αικατερίνη, Agia Aikaterini) to the east of the city, dating to at least the early 19th century. The latter hypothesis influenced official usage in Greek, where the city is found as "Aikaterini" (Greek: Αικατερίνη) or "Agia Aikaterini" (Greek: Αγία Αικατερίνη) until the early 20th century, when the vernacular name Katerini (Greek: Κατερίνη) prevailed.

According to the reports of travellers, at the turn of the 19th century, the city had four to five thousand inhabitants, mostly Greeks. In 1806, William Martin Leake recorded 100 hearths, while four years later Daniel recorded 140. For the remainder of the 19th century, the number of homes remained steady at about 300, with a population in 1900 of 2,070 Orthodox Christians and 600 Muslims.

The city was liberated by the Greek 7th Infantry Division from the Ottoman rule and annexed to the Greece on 16 October 1912, during the First Balkan War. It has been part of Greece since then. Refugees from the Greek genocide settled in Katerini. With the population exchange between Greece and Turkey in 1923 the city's Muslims were expelled, while Greek refugees from Eastern Thrace and Greek Evangelicals from Asia Minor took their place, almost doubling the city's population from 5,540 in 1920 to 10,138 in 1928.

During Axis Occupation of Greece by the Axis Powers in World War II, Katerini went under Nazi German occupation on 14 April 1941, and was liberated on 26 October 1944.

The Municipality of Katerini was formed in 2011 with the Kallikratis Programme administrative reform by the merger of the following 6 former municipalities, that became municipal units of the newly formed Municipality of Katerini.

The municipality Katerini is subdivided into 6 municipal units, each of which is divided into municipal communities.