Shmygal had served as prime minister since 2020, steering the Ukrainian government through the COVID-19 pandemic and the start of Russia's full-scale invasion in 2022.

Economy minister Yulia Svyrydenko is expected to take Shmygal's place, while current defence minister Rustem Umerov may become ambassador to the United States, Zelensky said last week.

The reshuffle, the biggest since Russia invaded in 2022, comes after months of battlefield setbacks and escalating Russian aerial attacks on Ukrainian cities.

"Denys Shmygal's vast experience will certainly be useful in the position of Minister of Defence of Ukraine," Zelensky said in his evening address, without providing further detail.

Shmygal's appointment will require approval from parliament, which has largely coalesced around Zelensky since the invasion and is unlikely to vote against him.