Ordu (Turkish pronunciation: [ˈoɾdu]) or Altınordu is a port city on the Black Sea coast of Turkey, historically also known as Cotyora or Kotyora (Pontic: Κοτύωρα), and the capital of Ordu Province. The city forms the urban part of the Altınordu district, with a population of 235,096 in 2023.

Kotyora, the original name of the city is a legacy of indigenous Colchians. The name is allegedly composed of an old Laz language word for pottery ('Koto', similar to Mingrelian 'Koto', Georgian 'Kotani' and Laz 'Katana') and a common Kartvelian suffix indicating belonging ('Uri'). In Zan (aka Colchian) Kotyora means a place where pottery is made. This point is supported with several other Kartvelian place names existing in the region as well as the region itself historically being known as Djanik (Djani being another name for Laz).

The contemporary name of Ordu meaning 'army camp' in Ottoman Turkish was adopted during the Ottoman Empire because of an army outpost being located near the present day city.

In the 8th century BC, Cotyora (Κοτύωρα) was founded by the Miletians as one of a string of colonies along the Black Sea coast. Diodorus Siculus wrote that it was a colony of the Sinopians. Xenophon's Anabasis relates that the Ten Thousand rested there for 45 days before embarking for home. Strabo also mentions it. Under Pharnaces I of Pontus, Cotyora was united in a synoikismos with Cerasus. Arrian, in the Periplus of the Euxine Sea (131 CE), describes it as a village "and not a large one." Suda mentioned that it was also called Cytora (Κύτωρα).

The area came under the control of the Danishmends, then the Seljuk Turks in 1214 and 1228, and the Hacıemiroğulları Beylik in 1346. Afterwards, it passed to the dominion of the Ottomans in 1461 along with the Empire of Trabzon.

The modern city was founded by the Ottomans as Bayramlı near Eskipazar as a military outpost 5 km (3 mi) west of Ordu.

In 1869, the city's name was changed to Ordu and it was united with the districts of Bolaman, Perşembe, Ulubey, Hansamana (Gölköy), and Aybastı. At the turn of the 20th century, the city was more than half Christian (Greek and Armenian), and was known for its Greek schools.

On 4 April 1921, Ordu province was created by separating from Trebizond Vilayet.

In 2016, archaeologist discovered a marble statue of Cybele. In 2018, at the same site, they also discovered sculptures of Pan and Dionysus. In 2021, archaeologists complained because a stone quarry used dynamite destroying some of the rock tombs.

In December 2021, archaeologists announced 1600 year-old eight tombs in the Kurtulus district of Ordu. Researchers also uncovered human and animal remains, many pieces of jewelry made of gold, sardine stone, silver, glass, and bronze, a glass bottle and beads. In the same area researchers unearthed a Byzantine monastery church and they determined it was dedicated to the Emperor Constantine and his mother Helena.

The Sağra factory shop, selling many varieties of chocolate-covered hazelnuts, is one of the town's attractions.

The Boztepe aerial tramway is another popular attraction which is set to become a modern symbol for the city.

Local music is typical of the Black Sea region, including the kemençe. The cuisine is primarily based on local vegetables and includes both typical Turkish dishes — such as pide and kebab — and more interesting fare such as plain or caramel 'burnt ice-cream'.

Ordu is one of the provinces where hazelnuts are grown the most in Turkey. Ordu is famous for hazelnuts, producing about 25 percent of the worldwide crop. The province relies on the crop for up to 80% of its economic activity. Turkey as a whole produces about 75 percent of the world's hazelnuts. As of 1920, Ordu was one of the few producers of white green beans, which were exported to Europe. Ordu also had mulberry tree plantations for sericulture. Today, the city is partially industrialized and a member of the Anatolian Tigers with its 7 companies.

• Paşaoğlu Konağı and Ethnographic museum – an ethnographic museum.
• Taşbaşı Cultural Centre – a cultural centre
• Boztepe – a hill of 550 m (1,800 ft) overlooking the town from the west. Since June 2012, an aerial lift system provides an easy way of transportation between the city's coastline and the hilltop. The Ordu Boztepe Gondola can transport hourly 900 passengers up to the hilltop in 6.5 minutes.
• Old Houses of Ordu in the old city center
• Yalı Camii, also called Aziziye Camii – a mosque
• Atik İbrahim Paşa Camii, also called Orta Cami – a mosque built in 1770
• Eski Pazar Camii – a mosque with adjoining Turkish baths
• Efirli Camii – a mosque
• Cape Jason is an Archaeological site and a small peninsula facing the sea. Its name is derived from the Mythological leader Jason of the Argonauts.

The city is the home of the Orduspor football club. Its base is the 19 Eylül Stadium in the heart of the city. Orduspor football team has played in the Super League of Turkey several seasons. The club also has a basketball team.

Ordu is twinned with:

• Batumi, Georgia, since 2000
• Ganja, Azerbaijan

Ordu has a humid subtropical climate (Köppen: Cfa, Trewartha: Cf), like most of the eastern Black Sea coast of Turkey. It experiences warm summers, cool winters, and plentiful precipitation throughout the year, which is heaviest in autumn and winter.

Snowfall is occasional between the months of December and March, snowing for a week or two, and it can be heavy once it snows.

The water temperature, like in the rest of the Black Sea coast of Turkey, is always cool and fluctuates between 8 and 20 °C (46 and 68 °F) throughout the year.

• Gülşen – singer
• Ertuğrul Günay – politician who is a former Ministry of Culture and Tourism (Turkey)
• Kadir İnanır – actor
• İdris Naim Şahin - politician
• Mehmet Hilmi Güler – politician who was Ministry of Energy and Natural Resources and current mayor of the Ordu Province.
• Numan Kurtulmuş – politician
• Terzi Fikri – comunist politician and old Fatsa mayor.
• Kamil Sönmez – Black Sea region at Turkish folk music artist
• Soner Arıca – musician
• Erdoğan Arıca – footballer

• 1977-1980 and 1984-1994 Kazım Türkmen CHP, SODEP, SHP
• 1994-2004 Fikret Türkyılmaz ANAP, MHP
• 2004-2014 Seyit Torun DSP, CHP
• 2014-2018 Enver Yılmaz AK Party
• 2018-2019 Engin Tekintaş AK Party
• 2019-present Hilmi Güler AK Party

• Orduspor
• 52 Orduspor
• Orduspor 1967

• Municipality of Ordu
• Kotiora (Ordu)