Mykolayiv was founded in 1789 in the aftermath of the Russian-Turkish war of 1768-1774 together with neighbouring cities of Kherson 1778 and later Odesa 1794. The name was given after the sailors' friend Saint Nicholas and also after the day in December 1788 when general Suvorov captured major Turkish fortress of Achikale now Ochakov/Ochakiv, in 60 km from Mykolayiv. The first ship "St. Nicholas" was built in 1790.

From the beginning Mykolayiv became the navy shipbuilding centre of the Russian Empire. Mykolayiv was governed by a military governor until 1900. The oldest shipyard modern name '61 Communars' was founded one year earlier than the city in 1788. Soldiers, craftsmen and free people from various areas of Russian Empire were ordered to Mykolayiv. Some streets still have numbered names according to founders' occupation: 11th Voennaya Military or 9th Slobodska Free settler. The city was well planned from the beginning. Main streets are wide and were used to carry wood to the shipyards. Glamorous parks make a big portion of the city. Downtown area is located on the peninsula made by Southern Bug and Ingul rivers estuary. The Black Sea navy headquarters was located in Mykolayiv for more than 100 years until it moved to Sevastopol.

Shipbuilding is a part of Mykolayiv history. There are three shipyards in Mykolayiv and the only Shipbuilding University in Ukraine. Mykolayiv was closed to foreign visitors until the late 1980s because of large navy projects as well as Air Force base, turbine plant and military port.

Mykolayiv was major Jewish centre of Russian Empire in 19th century. The Lubavitcher Rebbe, Rabbi Menachem M. Schneerson the seventh leader in the Chabad-Lubavitch dynasty was born in Mykolayiv on April 18, 1902.

Today the city has a population of about 500,000. The official language is Ukrainian, but Russian is widely spoken and English is also commonly spoken.