42-а механізована бригада is a unit of the Ukrainian Ground Forces, established on January 25, 2023. The brigade’s formation was overseen by the Ivano-Frankivsk Recruitment Center and consisted predominantly of mobilized personnel from western Ukraine. A number of officers and non-commissioned officers were transferred from the 10th Mountain Assault Brigade, contributing to the unit’s cohesion, motivation, and ability to adapt to changing battlefield conditions.
The brigade became the first unit of the Ground Forces — and the second formation overall — to receive Stryker armored personnel carriers. However, the equipment was later reassigned to Air Assault units.
In June 2023, the brigade was deployed to the Serebryansk Forest area, and in the autumn of the same year to the outskirts of Bakhmut. In May 2024, it was redeployed to the Kharkiv sector to assist the 125th Territorial Defense Brigade in repelling a Russian offensive.
In September 2024, a battalion tactical group formed from elements of the 42nd Mechanized Brigade was attached to the 100th Mechanized Brigade, which was defending Toretsk. The battalion tactical group withdrew in July 2025.
In August 2025, another battalion tactical group was formed and assigned to the Chervona Kalyna Brigade of the National Guard.
As of December 2025, the brigade was assessed to be operating at approximately 20 percent of its strength.