The new Chief of the General Staff, Andrij Gnatov, "has been tasked with increasing the efficiency of army leadership", it says in a statement.
He replaces Anatolij Barhylevytj, who has held the role since February 2024.
Ukraine's military, which has grown significantly since Russia's full-scale invasion in February 2022, is in the process of reorganization aimed at improving coordination.
"This includes restructuring the command system and implementing clear norms", writes Rustem Umerov on his Facebook page.
The announcement comes just hours after Ukraine's military confirmed that they had withdrawn from Sudzja in Russia's Kursk region, a community described as a crucial hub for Ukraine's presence in the region.
It was in August last year that Ukraine made an unexpected incursion into the Russian border region and took control of an area of over 1,300 square kilometers. They dug in in the region, but have recently lost ground.
