Mykolaiv is a strategically important shipbuilding and port city on the Black Sea and on 4 March was "seen as the next key stepping-stone for Russian forces on the road to Odesa.

Residents were in a state of panic regarding Russian troop movements in nearby Kherson, and a lack of communication among security forces led to friendly fire incidents.

Over the course of the battle, he reportedly refused eight orders to blow up the Varvarivskyi Bridge over the Southern Bug River, which would have caused the city to become totally encircled.

[36][37] Russian soldiers, termed "little green men" by locals, were filmed moving through the city's northern micro-district [uk] in armored vehicles.

[47] On 28 February, Russian troops advanced from Kherson towards Mykolaiv, reaching the city's outskirts and launching an assault at 11:00 a.m. local time.

[51][52][53][54][55] On 2 March, another Russian column was defeated at the city of Voznesensk, northwest of Mykolaiv, by Ukrainian regular army troops, members of the Territorial Defense force, and local volunteers.

[57][58] Mayor Sienkevych said Mykolaiv was preparing for urban combat, and called on "everyone who could hold a weapon" to join in the city's defense.

[58] On 3 March, the Ukrainian military claimed that the Russian landing party in Balovne, which it said consisted of airborne troops of Russia's 10th Special Forces Brigade had been "destroyed".

Hundreds of Russian tanks moved towards the city from three directions: Stanislav to the south, Posad-Pokrovske to the southeast, and from the north, down the highway connecting Mykolaiv and Kropyvnytskyi.

Two Russian BTRs entered the Kulbakynskyi airfield, which Marchenko recognized as a feint designed to draw out Ukrainian reserves and artillery.

Ukrainian troops held a single swing bridge spanning the Southern Buh, the easiest route for Russian forces to reach the port of Odesa.

[66][67] On 7 March, ten Ukrainian soldiers were killed and dozens of others were wounded in a Russian airstrike on the barracks of the 79th Air Assault Brigade at 05:15.

[70] At 05:00 Russian troops began shelling the city and a Kalibr cruise missile hit a military barracks, killing eight soldiers and wounding 19, while another eight were missing.

[71] Kim claimed on 11 March that Ukrainian forces had pushed Russian troops back to the east by 15–20 kilometres (9–12 mi) and had also surrounded some units who were negotiating for a surrender.

[72] Russian forces still controlled villages 20 kilometres (12 mi) away, with only the Southern Bug River keeping the city from being encircled.

Ruslan Khoda, who commanded the Ukrainian forces defending the airport, stated that Russian troops seemed to be mounting probing attacks to test vulnerabilities in their defenses and they were often preceded by surveillance drones.

Maj. Gen. Dmytro Marchenko, who was leading the city's defense, stated that Ukrainian forces were trying to break the morale of Russian troops by repeatedly shelling them.

[69] Units of Ukraine's 28th Mechanized Brigade went on the offensive south of the city on 12 March, when they captured the villages of Prybuzke [uk] and Ukrainka.

Yuri Biryukov, an associate of Major General Dmitry Marchenko, commander of the Nikolaev defense forces, claimed on 15 March their troops had killed 200 Russians and had taken "trophy heaps of weapons and ammunition".

[18] On 19 March, the Ukrainian General Staff claimed to have killed 200 "DPR mobilized soldiers" over the past two days, and that others had become "demoralized" and refused to fight.

Subsequently the people in Mykolaiv were forced to rely on water from rivers and streams as well as donations from neighboring towns and cities.

The exiled governor of the Kherson region at that time, Dmytro Butrii, told the BBC that the Russian occupation forces did not allow a repair team to access it.

[96] Olha Dierugina, the director of the forensic institute of Mykolaiv, told Agence France-Presse that their morgue had received 120 bodies during the battle, including 80 soldiers and 30 civilians.