Lebanon's political parties have chosen Saad Hariri to be prime minister, a year after he stepped down in the face of mass anti-government protests.
Mr Hariri was asked to form a new government after he secured the backing of a majority of members of parliament.
Protesters began demanding a complete overhaul of the political system last October amid a deep economic crisis.
The country has been pushed further to the brink by the Covid-19 pandemic and August's devastating blast in Beirut.
The disaster, which many blamed on government negligence, prompted the resignation of Mr Hariri's successor, Hassan Diab.
The man nominated to replace him, Mustapha Adib, quit last month after failing to win enough support for his non-partisan cabinet line-up.
That dealt a blow to a French initiative that requires Lebanon's politicians implement urgent reforms and tackle corruption in return for billions of dollars of international aid.
In a televised address on Wednesday, President Michel Aoun complained that lawmakers and officials were blocking steps that they had previously agreed.
"Where are all the reforms? Where are all the clauses that were presented to the heads of [parliamentary] blocs and parties?" he asked.
"The silence of any official, and lack of co-operation in the forensic audit [of the central bank], prove he is a partner in corruption and waste."
Why is Lebanon in crisis?
During Mr Hariri's previous term in office, Lebanon's economy began to collapse.
The country, which is one of the most indebted in the world, saw growth fall to zero and its pegged currency lose value on the black market as a result of a shortage of US dollars.
Unemployment and poverty were also rising, and people were getting increasingly angry about the government's failure to provide even basic services.
The protests that eventually forced Mr Hariri to resign erupted after his cabinet proposed a tax on voice calls via messaging services such as WhatsApp to help raise revenue.
The unrest rapidly turned into a nationwide revolt against a political elite that many Lebanese have long accused of corruption, waste, mismanagement and negligence.
A key demand of the protesters was a government led by independent technocrats.
Power in Lebanon is largely based on sectarian interests. Political appointments and many jobs depend on belonging to one of the country's 18 officially recognised religious communities - a situation that has led to patronage and cronyism.
The National Pact of 1943 declares that the president must be a Christian, the prime minister a Sunni Muslim, and the speaker of parliament a Shia Muslim.