The election, the first to be held in nine years, was marked by a lower turnout than before, reflecting voter frustration over endemic corruption and a stagnant economy.
Hezbollah leader Hassan Nasrallah called the vote "a great political and moral victory for the resistance option that protects the sovereignty of the country".
Astute pre-electoral tactics have secured Hezbollah enough allies to withstand political challenges on strategic issues.
Hariri, a Sunni politician with close ties to Saudi Arabia, has so far lost five seats in Beirut, once considered a stronghold for his party.
Hariri said his Future Movement had won 21 seats in the parliamentary election, down from the 33 he won the last time Lebanon elected a parliament in 2009.
"We were betting on a better result and a wider bloc with better Christian and Shiite participation", he said.
Hezbollah's simple majority bloc will allow them to veto any laws they oppose, but it would take a two-thirds majority to pass big legislation, such as amending the constitution. The United States designates Hezbollah as a terrorist group and also arms and trains the Lebanese army. Lebanon's prime minister has to be a Sunni under its power-sharing system.
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The university is the only privately funded college in North Korea and was founded in 2010 with donations from Christian groups. He's previously said the summit was planned for May or early June. 'I won't use the rhetoric now, ' he said.
Hezbollah's allies include the Amal Movement led by Parliament Speaker Nabih Berri and the Christian Free Patriotic Movement founded by President Michel Aoun.
Lawmakers had extended their own mandate three times since 2009, ostensibly over security concerns linked to the war in neighbouring Syria and political divisions that led to long and crippling institutional crises.
Turnout stood at a lowly 49 percent, according to official figures released after Sunday's vote by the interior ministry.
Some voters also said that the sometimes absurd web of local alliances that saw some parties work together in one district and compete in others had put them off.
Iran maintains that holding a peaceful election amid the current chaotic situation of the region is by itself a great democratic achievement for all the people of Lebanon, he added.
The prime minister still heads the largest parliamentary bloc and will likely form a new national unity cabinet.
Initial indications showed the staunchly anti-Hezbollah Lebanese Forces, a Christian party, emerging as a big victor, almost doubling its lawmakers to at least 15 from eight.