Hariri is in Paris at the invitation of France's President Emmanuel Macron, who is attempting to help broker a solution to a political crisis that has raised fears over Lebanon's fragile democracy.
Hariri and his wife Lara, who landed at Le Bourget airport outside the French capital at 7:00 am (0600 GMT) after flying in from Riyadh overnight, were due to meet Macron at noon.
A source close to the premier told AFP that Hariri's two youngest children, Loulwa and Abdelaziz, born in 2001 and 2005 respectively, had stayed behind in Riyadh "for their school exams".
"Hariri does not want to mix his children up in this affair," the source said.
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The couple were whisked to their Paris residence in a seven-car convoy under tight security.
"To say that I am held up in Saudi Arabia and not allowed to leave the country is a lie," Hariri had tweeted just before his departure, adding to repeated denials of the rumours from Saudi officials.
A source close to Hariri said the premier had held an "excellent, fruitful and constructive" meeting with powerful Saudi Crown Prince Mohammed Bin Salman before he left.
He said he feared for his life, accusing Iran and its powerful Lebanese ally Hezbollah of destabilising his country.
But Hariri's failure to return from Saudi Arabia prompted claims he was essentially being held hostage there, including from Lebanese President Michel Aoun who refused to accept his resignation from abroad.
Hariri's resignation was widely seen as an escalation of the battle for influence between regional arch-rivals Sunni Saudi Arabia and Shiite Iran, which back opposing sides in the conflicts in Syria and Yemen.
Hariri met French Foreign Minister Jean-Yves Le Drian in Riyadh on Thursday as Paris, which held mandate power over Lebanon for the first half of the 20th century, seeks to ease the crisis.
In another development, Riyadh today recalled its ambassador to Berlin in protest at comments by Germany's Foreign Minister Sigmar Gabriel which were interpreted as a suggestion that Hariri acted under Saudi orders.
Without mentioning Saudi Arabia directly, Gabriel had on Thursday said he shared concerns about the threat of instability and bloodshed in Lebanon and warned against "adventurism".
Ahead of Hariri's departure, the Lebanese president -- an ally of Hezbollah -- welcomed the announcement of the trip to Paris, expressing hope that it was the "start of a solution".