Turkish lawmakers began taking their oaths at the parliament in capital Ankara on Saturday.
The general assembly convened at 2 p.m. (1100 GMT) under the chairmanship of Acting Speaker Durmus Yilmaz.
Yilmaz took his oath first in the 600-seat strong parliament.
Lawmakers also observed a moment of silence for Turkish Republic's founder Mustafa Kemal Ataturk when the time came for lawmakers to take their oath.
On Monday, Erdogan will be sworn in as president for the first time under the new executive presidential system.
The president's swearing-in ceremony will be held at 4 p.m. local time (1300 GMT) at the parliament in capital Ankara, a source said on condition of anonymity due to restrictions on talking to the media.
Later, a ceremony will be held at the presidential complex to mark the country’s transition to the presidential system of governance.