The three will discuss steps that can be taken to end the Ukraine-Russia conflict through diplomatic means.
Türkiye's President Recep Tayyip Erdogan has arrived in the Ukrainian city of Lviv for talks with his Ukrainian counterpart and the UN chief.
Before meeting Ukrainian President Volodymyr Zelenskyy on Thursday, Erdogan will lay a wreath at the historic Lychakiv Cemetery.
He will hold a bilateral meeting with Zelenskyy at the Potocki Palace and discuss all aspects of Türkiye-Ukraine relations at the strategic partnership level.
The bilateral talks will be followed by a trilateral summit with Guterres. They are expected to hold a joint news conference after the trilateral meeting.
The three will discuss steps that can be taken to end the Ukraine-Russia conflict through diplomatic means, by increasing the activities of the mechanism established for the export of Ukrainian grain to the world markets, according to the Turkish presidency.
On July 22, Türkiye, the UN, Russia, and Ukraine signed an Ankara-brokered deal in Istanbul to reopen three Ukrainian Black Sea ports for exporting Ukrainian grain stuck due to the Russia-Ukraine conflict, which is now in its sixth month.
To oversee the process, the Joint Coordination Center (JCC) in Istanbul was officially launched on July 27, comprising representatives from the three countries and the UN, to enable the safe transportation of commercial foodstuffs and fertilisers by merchant ships.
According to the UN, Guterres is also scheduled to visit the Ukrainian port city of Odessa to view the movement of grain following the trilateral meeting.
Guterres will head to Türkiye on Saturday and visit the JCC in Istanbul.