Mr Saied appointed Nabil Ammar, the Tunisian ambassador to Brussels, to succeed Othman Jerandi, who has held the position since September 2022.
The reasons for Mr Jerandi's dismissal were not disclosed.
Many observers expected the reshuffles to continue as Tunisia goes through its worst economic crisis, and with popular dissatisfaction about the government’s performance increasing.
Mr Saied announced the formation of his current government in October 2021, after his enactment of a "state of exceptional measures".
Since then he has ruled the country through presidential decrees and continued to monopolise executive powers.
The current government is Tunisia's 13th since its uprising in 2011.