A statement by Hariri's media office on Tuesday said the prime minister would meet Saudi King Salman and Crown Prince Mohammed bin Salman, without offering details on the agenda.
The state visit by Hariri, who also has Saudi citizenship, comes in advance of parliamentary elections in Lebanon on May 6, and of major donor conferences aimed at supporting Lebanon.
Gulf nations, and in particular Saudi Arabia, are seen as potential donor countries to these conferences.
Hariri last travelled to the kingdom on November 3 and unexpectedly resigned in a televised statement a day later.
His address from his home in Riyadh sparked outrage in Lebanon over what was publicly perceived as the abduction of a sovereign state's prime minister by another country.
The move put Saudi-Lebanese relations to the test with President Michel Aoun refusing to accept the resignation and calling on authorities in Riyadh to release his country's "detained" prime minister.
Hariri, for his part, accused Iran and Hezbollah of destabilising Lebanon and remained in the Saudi capital for two weeks. He was reportedly held there until France intervened.
Lebanon has been caught in the rivalry between Saudi and Iran, both aiming to extend their influence in the region.
Hariri, 47, ultimately returned to Beirut weeks later after French President Emmanuel Macron's successful mediation efforts, and withdrew his resignation.