Anadyr is a port town and the administrative centre of Chukotka Autonomous Okrug, the extreme north-eastern region of Russia. It is at the mouth of the Anadyr River, on the tip of the southern promontory that sticks out into Anadyrskiy Liman. At 177°30′E, Anadyr is the easternmost town in Russia (more easterly locations, such as Provideniya and Uelen do not have town status by the Russian definition). It was founded on July 21, 1889 as Novo-Mariinsk, and renamed on August 5, 1923 following the Kamchatka Revkom. Town status was granted on January 12, 1965.

Although the town itself has only been in existence for just over a century, the origins of the name Anadyr are much older. The name initially derives from the Yukaghir word "any-an" meaning "river". When Semyon Dezhnev met Yukaghir peoples in the area and the indigenous name was corrupted to form "Onandyr", later Anadyrsk, the name of the ostrog (fort) upstream of the present-day settlement, from which the current name is derived.

Pyotr Baranov (brother of Alexander Andreyevich Baranov) established a trading post near the present town site in the early 19th century; Chukchi settlement around it formed the village of Vyon in 1830.

The present settlement was founded by L. F. Grinevetsky, who sailed into the Anadyrskiy Liman on July 9, 1889. The town's first building was completed 12 days later and as it was the name-day of Tsarista Maria Feodorovna the town was named Mariinsk. Since this was not the first time that a town had been named Mariinsk in Russia, the name was swiftly changed to Novo-Mariinsk.

The presence of Communism was not initially welcomed by the merchants of the town. The first Revkom was founded on January 16, 1919 and barely lasted 2 weeks before its members were thrown out of the town and summarily executed. However, the merchants of the town fared worse 18 months later when the Bolsheviks returned and began to reorganise urban life.

The town originally also incorporated other urban-type settlements such as Ugolnye Kopi, Shakhtyorsky and villages (selos) such as Tavaivaam, but these are independent settlements.

Although Anadyr is the largest town in the whole of Chukotka Autonomous Okrug, and the Administrative centre of the Okrug, it is not the Administrative centre of Anadyrsky District, which is in Ugolnye Kopi.

Anadyr is an important sea port on the Gulf of Anadyr of the Bering Sea and is connected to almost all big Russian Far Eastern sea ports. The Anadyr Ugolny Airport serves major and minor cities in the Russian Far East with connections to Khabarovsk, Vladivostok and Moscow, and Bering Air charter flights to Nome, Alaska. The airport is on the other side of the Anadyrskiy Liman and between January and May transportation from the airport to Anadyr is by ice road.

Anadyr experiences a subarctic climate (Köppen climate classification Dfc). The weather in Anadyr is extremely changeable, with heavy storms often being brought in from the Anadyrskiy Liman and the Bering Sea. This coupled with strong southerly winds in the autumn often brings flooding to the area.