President Recep Tayyip Erdogan had arrived in Buenos Aires on Thursday to attend the summit.
Argentine President Mauricio Macri -- also this year's President of the G20 Summit -- welcomed the G20 leaders at the Costa Salguero Center.
Later, Erdogan and other heads of state attended the special session -- entitled Fair And Sustainable Future.
Before the session, Turkish president had a brief chat with his U.S. counterpart Donald Trump.
The G20 leaders will also attend the opening of the summit, where Macri will deliver a speech, after the session.