Hariri won the backing of a majority of parliamentarians in consultations with Aoun on Thursday.
The prime minister-designate, who has previously led three governments in Lebanon, stepped down almost a year ago under pressure from unprecedented protests against economic hardships.
Hariri vowed Thursday to quickly form a new Cabinet of nonpartisan specialists.
He faces major challenges to navigate Lebanon’s power-sharing politics and agree a cabinet, which must then address a mounting list of woes: a banking crisis, currency crash, rising poverty and crippling state debts.
A new government will also have to contend with a COVID-19 surge and the fallout of the huge August explosion at Beirut port that killed nearly 200 people and caused billions of dollars of damage, according to Reuters.
Hariri’s last coalition government was toppled almost exactly a year ago as protests gripped the country, furious at Lebanon’s ruling elite.