|Hariri was appointed prime minister after his coalition emerged victorious in June 7 polls [EPA]
Saad Hariri was thrust into the midst of Lebanese politics in 2005 following the assassination of his father, Rafiq al-Hariri, the country's former prime minister, in a bombing in central Beirut.
The younger Hariri took centre-stage on Saturday when Michel Sleiman, Lebanon's president, appointed him as prime minister.
He is entrusted with forming a new government to help the country emerge from four years of political turmoil.
The 39-year-old businessman rose through the ranks of Lebanon's opposition following his father's death, which supporters blamed on Damascus and pro-Syrian elements of Lebanon's government.
Damascus maintains it had no responsibility in the killing.
Saad Hariri went on to head his father's party, the Future bloc (al-Mustaqbal), the largest group within the March 14 coalition, Lebanon's majority bloc in parliament.
The Future bloc, which draws its support mainly from the country's Sunni population, later formed alliances with other parties, including the Progressive Socialist Party, the favoured political vehicle of the Druze community, and the Lebanese Forces, with a strong following among Christians.
Al-Hariri led his Western-backed coalition to victory against the Iranian- and Syrian-backed Hezbollah and its allies in the country's June 7 poll, winning 71 out of the 128 parliaments seats.
In the 2005 parliamentary elections, Hariri's March 14 camp ran on an anti-Syria platform, calling on Damascus to end its alleged interference in Lebanese affairs.
Following the alliance's victory in that election, al-Hariri was tipped to become Lebanon's prime minister, a post reserved for a Sunni Muslim under the country's sectarian power-sharing system.
But he declined the post, recommending the selection of Fouad Siniora, an economist and finance minister during the prime ministerial terms of Rafiq al-Hariri.
Born in Saudi Arabia on April 18, 1970, Saad Hariri went on to head his father's Saudi-based construction company, Saudi Oger, one of the largest companies in the Middle East.
Many now regard Saad Hariri is a success in the business world in his own right, with a net worth of about $1.4bn, albeit down from 3.3bn last year, according to Forbes magazine's 2009 list of the world's billionaires.
When Saad Hariri entered Lebanese politics following his father's death four years ago, critics chided him for his lack of political experience.
But he has since emerged as a powerful political force, and led the way in negotiating the formation of a unity government in Lebanon in May 2008.
The move helped bring an end to a dangerous stalemate that had led Lebanon to the brink of another civil war.
Saad Hariri attributes part of his political success to public sympathy for his father.
Rafiq al-Hariri headed five governments and is considered the driving force behind the country's reconstruction following civil war and foreign invasion between 1975 and 1991.