Hariri resigned in a televised address on November 4 from Saudi Arabia and then remained in Riyadh, where he spent two weeks before leaving for Paris.
His resignation shocked Lebanese, but Hariri's prolonged stay in Saudi Arabia proved even more mysterious for many and sparked accusations that he was being held hostage in the kingdom.
He denied claims he was being detained, and promised to return to Lebanon in time to join Wednesday's celebrations for Independence Day.
His plane touched down at Beirut airport shortly before midnight, a statement from his office said, and he was expected to attend an Independence Day military parade before participating in the traditional reception at the presidential palace.
His Future Movement has called on supporters to gather at his home in downtown Beirut at 1:00 pm.
He arrived in Beirut after stops in Cairo to see Egyptian President Abdel Fattah al-Sisi, and Cyprus, where he met President Nicos Anastasiades.
A dual Saudi citizen who has previously enjoyed Riyadh's backing, Hariri resigned in a mysterious broadcast from the Saudi capital, accusing arch rival Iran and its powerful Lebanese ally Hezbollah of destabilising his country.
But President Michel Aoun has yet to accept Hariri's resignation, insisting that he present it in person once back in the Lebanese capital.
During Hariri's two-week stay in Riyadh, Aoun accused Saudi authorities of holding him "hostage" and demanded that he enjoy freedom of movement.
After mediation efforts by Egypt and France, which held mandate power over Lebanon between the world wars, the 47-year-old premier left Riyadh on Saturday.
He headed to Paris for talks with French President Emmanuel Macron and pledged he would be home by Wednesday.
"As you know I have resigned, and we will discuss that in Lebanon," he said.
Hariri's resignation from outside the country is unprecedented in Lebanese history.
Questions remain over whether the resignation will stand, forcing negotiations on a new government, or if he might withdraw it.
Under Lebanon's constitution, the president is bound to accept a premier's resignation however it is tendered, Lebanese constitutional expert Edmond Rizk told AFP.
Although it is not outlined in the constitution, Rizk said, custom dictates "this resignation is supposed to be submitted to the president".
A resignation brings down the government, and the president then engages in consultations to select a new prime minister to form a cabinet.
In Lebanon, divided for more than a decade between a pro-Saudi camp and a Tehran-backed alliance, that process typically takes months of political wrangling.
But the discussions also aim to strike a balance between the country's diverse religious communities.
As part of Lebanon's presidential-parliamentary system, the premier must be a Sunni Muslim, the president a Maronite Christian and the speaker of parliament a Shiite Muslim.
More than a week ago, Hariri said he could withdraw his resignation if Hezbollah withdrew from regional conflicts.
Hezbollah, whose forces are fighting in neighbouring Syria along government troops, said it still considers Hariri the premier.
"When he comes, we will see. We're open to all dialogue and discussion," its chief Hassan Nasrallah said on Monday.
But if Hariri stands firm, Aoun has two options -- rename him premier or choose another prominent Sunni figure to lead a new cabinet.
"If Hariri's consultations lead to a new government, that would be a way out," said Rizk.
Aoun tipped Hariri as premier in 2016, as part of a deal across political lines that ended a two-and-a-half year stalemate in Lebanon.
Hariri's two terms as prime minister have both ended abruptly.
In January 2011, as he was meeting then-US president Barack Obama in Washington, Hezbollah and its allies withdrew their ministers and brought down Hariri's government.
His unexpected resignation earlier this month was seen as part of an escalating power struggle between Sunni Saudi Arabia and Shiite Iran, which back opposing sides in the conflicts in Syria and Yemen.
On the day Hariri resigned, the kingdom said it intercepted a ballistic missile fired at Riyadh airport by Shiite rebels in Yemen.
The announcement also coincided with a purge of more than 200 Saudi princes, ministers and businessmen.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)