A presidential decree announced the dismissal of Andriy Smyrnov, who was responsible for legal policy matters, and Oleksiy Dniprov, who headed the office's "apparatus". They were among 10 deputies to Zelenskiy's chief of staff, Andriy Yermak.
Appointed in their place were Olena Kovalska, who has been part of a group advising the president on the creation of a tribunal to prosecute Russia over its invasion of Ukraine, and Iryna Mudra, who has served as deputy justice minister.
Zelenskiy has overseen sweeping changes in senior positions, particularly among top military officers, appointing Oleksandr Syrskyi as commander in chief last month to replace the country's popular commander Valeriy Zaluzhyi.
In his nightly video address, Zelenskiy said he had appointed Oleksiy Danilov, former head of Ukraine's Security and Defence Council, as ambassador to Moldova, saying Danilov had wanted a diplomatic appointment.
The president described Moldova, whose pro-European President Maia Sandu has denounced Russia's invasion, as "an extremely important state - both from the point of view of security challenges in the region, and from the point of view of bilateral cooperation".
Danilov was dismissed last week from his position of head of the Security Council.
(Reporting by Oleksaandr Kozhukhar in Kyiv; Writing by Ron Popeski; Editing by David Gregorio)
