The siege of Mariupol began on 24 February 2022 and lasted until 20 May, as part of the Russian invasion of Ukraine. It saw fighting between the Russian Armed Forces and the Ukrainian Armed Forces for control over the city of Mariupol in southeastern Ukraine. Lasting for almost three months, the siege ended in a victory for Russia and the Donetsk People's Republic, as Ukraine lost control of the city amidst Russia's eastern Ukraine offensive and southern Ukraine offensive; all Ukrainian troops remaining in the city surrendered at the Azovstal Iron and Steel Works on 20 May 2022, after they were ordered to cease fighting.

The Azov Assault Brigade is a formation of the National Guard of Ukraine formerly based in Mariupol, in the coastal region of the Sea of Azov, from which it derives its name. It was founded in May 2014 as the Azov Battalion, a self-funded volunteer militia under the command of Andriy Biletsky, to fight Russian-backed forces in the Donbas War. It was formally incorporated into the National Guard on 11 November 2014, and redesignated Special Operations Detachment "Azov", also known as the Azov Regiment. In February 2023, the Ukrainian Ministry of Internal Affairs announced that Azov was to be expanded as a brigade of the new Offensive Guard.