The deal covers the election of army chief Michel Suleiman as president, the formation of a national unity government and a ban on the use of weapons in any internal conflict.
Under the terms of the accord, parliament will convene within 24 hours to vote for a new president.
However, some Lebanese politicians at the talks said that the vote for a new head of state would go ahead on Sunday, filling a post vacant since November.
The Doha mediation talks came after marathon negotiations in an Arab-mediated bid to end a political crisis that erupted into deadly street battles earlier this month.
Under the terms of the new deal, the opposition is due 11 seats in the cabinet, while 16 seats will go to the parliamentary majority bloc.
The remaining three seats will distributed by the elected president.
The composition of the new cabinet means that the Hezbollah-led opposition holds veto rights over decisions reached by the cabinet. Previously, the opposition held six seats in the executive.
The opposition also won another of its demands - a revision to Lebanon's electoral law, which divides the country into smaller-sized districts.
The opposition had said that changes to the electoral law would allow for better representation of the country's various factions.
However, Mohammed Raad, Hezbollah's chief negotiator, downplayed the opposition's gain, saying "neither side got all it demanded, but [the agreement] is a good balance between all parties' demands".
Fouad Siniora, Lebanon's prime minister, said: "We should renounce resorting to violence as a means to settling our political disputes."
"Our diversity is what Lebanon is known for. We should not use this diversity as a tool for division."
Siniora also said that the Arab league now has the task of "mending Syrian-Lebanese relations".
Saad al-Hariri, the parliament majority leader, said a "new page in Lebanon's history" was being opened.
"This page should be dedicated to reconciliation. I know that the wound is deep ... my wound is deep as well. However, in this country, we can not but live together," he said.
The Qatar-hosted talks followed an Arab-mediated deal that brought an end to a week of fighting, prompted by government moves to ban Hezbollah's private communications network and sack the security chief at Beirut airport, who was alleged to have ties to Hezbollah.
The US described the Doha pact as a move in the right direction, despite the gains made by Hezbollah.
"We view this agreement as a positive step towards resolving the current crisis by electing a president, forming a new government and addressing Lebanon's electoral law," Condoleezza Rice, the US secretary of state, said in a statement.
But David Foley, a spokesman for the US state department, told Al Jazeera that recent violence in Lebanon could impact on Hezbollah's image.
"Hezbollah was prepared to turn its weapons against the Lebanese people - I think that's had a very big impact in Lebanon and around the Arab world."
Protest camp removed
Nabih Berri, Lebanon's parliament speaker and a key opposition leader, announced the immediate lifting of an 18-month-old sit-in by the opposition in Beirut, the Lebanese capital.
The protest began on December 1, 2006 when the opposition set up a sprawling tent city on streets leading to the offices of Fouad Siniora, the prime minister, in a bid to force him to step down.
Within an hour, trucks started clearing the tent city, which had paralysed the commercial heart of Beirut.
|The tent city was part of protests calling|
for the resignation of Fouad Siniora [AFP]
Large parts of the city centre had been transformed into a ghost town as a result of the tent city, forcing dozens of restaurants and businesses to shut down.
"In the name of the opposition, I call for the end to the sit-in, in downtown Beirut," Berri said.
"This is the start of a good era, and it has started here in Qatar."
Al Jazeera's Zeina Khodr, reporting from the Lebanese capital, said that a sense of relief had overcome those hoping for an end to the sit-in in Beirut.
She said: "Projects that have been delayed can now be expected to move forward, and shop owners feel that they can get their businesses back on track."
But Al Jazeera's James Bays, also reporting from Beirut, said that many Lebanese remain sceptical of the deal.
"Many of the people here want to know the full details of this agreement. They will also express their opinions once they know just what this agreement entails."
"However, others also think that while a deal may have been reached in Doha, these politicians will start bickering over another issue once they get back."
Source: Al Jazeera and agencies