Salam, son of former Prime Minister Saeb Salam, won support from the March 8 alliance, which includes Hezbollah politicians, and March 14, a slate that has support from Western powers.
He'll be tasked with forming a new Cabinet that will replace Prime Minister Najib Mikati, who resigned last month. Lebanon is scheduled for elections in June.
Druze leader Walid Jumblatt, who leads the pivotal Progressive Socialist Party, praised Salam as a consensus leader.
"Salam is the voice of moderation," he was quoted by The Daily Star newspaper in Lebanon as saying. "He's never said a bad word against the resistance (Hezbollah)."
Jumblatt said any future government needs to include Hezbollah, however. The Shiite movement holds key administrative positions in Lebanon's government, though it's designated as a terrorist organization by some Western governments.
Salam is an independent, but allied with the Future Movement, a March 14 member. He's expected to be named prime minister-designate this weekend.
The U.S. State Department this week urged U.S. citizens to avoid traveling to Lebanon because of the security threat from the Syrian civil war. Hezbollah Deputy Secretary-General Naim Qassem said in comments published by The Daily Star that Lebanon's "stability is in everybody's interest."