He described it as a “last opportunity” to save the country hit by multiple political and financial crises.
Mr Hariri, who resigned from the post a year ago amid nationwide protests against alleged widespread corruption and a flunking economy, was asked to form the country’s next government after he secured enough votes from politicians.
In the year since, Lebanon’s currency has plunged, losing nearly 80% of its value, while prices, unemployment and inflation have soared.
Lebanese have been unable to access their savings as banks imposed informal capital controls fearing a run on deposits.
A huge explosion in August in Beirut’s port, caused by thousands of potentially explosive chemicals stored in a warehouse, compounded the crises.
The blast defaced the capital, killing nearly 200 people and injuring more than 6,000.
The explosion is seen as further proof of an incompetent political class in charge of governing the small country since the end of its 15-year civil war in 1990.
Mr Hariri’s return to office is a setback for protesters who have been demanding change and see him as a symbol of a political class they blame for the country’s woes.
He pledged a government of non-partisan specialists tasked with implementing economic, financial and administrative reform, according to a French initiative that was endorsed by mainstream Lebanese politicians.
“I say to Lebanese who are suffering hardship to the point of despair, I intend to keep my promise, to work on stopping the collapse that threatens our economy, society and security,” Mr Hariri said in a brief statement on Thursday.
His successor, Hassan Diab – a technocrat supported by Hezbollah – stepped down after the August 4 explosion.
The blast prompted France, a long-time ally and former colonial ruler, to push for a new political order in Lebanon.
It launched what came to be known as the French initiative, designed to pressure rival politicians to reach an agreement on a government empowered to introduce wide-ranging economic reforms.
The international community has said it will not help Lebanon financially before reforms are implemented.
Lebanon’s complex sectarian-based political system makes reaching major decisions a significant challenge.
Power, including government posts, is distributed among the country’s Shi’ites, Sunnis and Christians.
Mr Hariri won by a simple majority on Thursday, securing a total of 65 votes out of 120 politicians polled by President Michel Aoun amid sharp divisions over the shape of the Cabinet he is expected to form.
The president had already delayed the consultations a week, amid signs of wrangling over his party’s role in any upcoming government.
In a speech on the eve of the consultations, Mr Aoun signalled he would not stop Mr Hariri from being named prime minister but indicated he wants a bigger role in government formation.
Most observers expect a rocky process.
“Today, I am required to designate (a prime minister) and then participate in the formation of a government,” Mr Aoun said.
“Will the one who is nominated commit to addressing corruption and launching reform?”
