The 21st Separate Mechanized Brigade (A4689) is a formation of the Ukrainian Ground Forces.
On 11 June 2023, during the 2023 Ukrainian offensive, it was reported that elements of the Brigade had taken part in an assault near Orikhiv in the Zaporizhzhia region involving German-made Leopard 2 tanks.
On 6 December 2024, armed forces day, the battle flag was presented to the unit by the President of Ukraine Volodymyr Zelenskyy.
The unit took part in combat in the eastern Bakhmut and north-eastern Kupyansk sectors. Later it thought at the Kharkiv front. The brigade was also one of the elements that operated in Russian territory during the Kursk campaign.
On 23 August 2025 the unit was awarded the honorary award For Courage and Bravery by the President.
21st Mechanized Brigade
The Brigade is equipped with western donated tanks and IFVs.