President Moon Jae-in arrived in New York on Sunday evening, local time for the UN General Assembly.
On Monday morning he is giving an address at the opening ceremony of a UN event on sustainable development.
As the only head of state to attend the session, Moon is expected to call for future generations to participate in helping to achieve sustainable development goals, and highlight the need for global cooperation and solidarity.
He will be joined by BTS special envoys for future generations and culture who will also give a speech.
Later in the day, the South Korean leader will hold bilateral summits with his counterparts from Slovenia and the UK as well as a meeting with UN chief Antonio Guterres.