The TV released a video of Prince Mohammed receiving Guterres, and the Saudi Press Agency (SPA) added later that the two leaders had reviewed aspects of the partnership between Saudi Arabia and the United Nations.
The G20 summit in Buenos Aires is the first major international event the Saudi prince has attended since the murder of journalist Jamal Khashoggi in the Saudi consulate in Istanbul in October.
After offering numerous contradictory explanations, Riyadh said last month that Khashoggi had been killed and his body dismembered when negotiations to persuade him to return to Saudi Arabia failed.
Saudi Arabia has said the prince had no prior knowledge of the murder, which has strained Saudi Arabia’s ties with the West and battered the prince’s image abroad.
The prince also met on Saturday with Italy’s Prime Minister, Giuseppe Conte, and reviewed bilateral relations, SPA said.
The agency added that the heir to the throne of the world’s top oil exporter had met the Argentinian president, Mauricio Macri, reviewing means to promote cooperation between the two countries.