The talks follow the collapse of an earlier truce amid recriminations.
The conflict pits powerful General Khalifa Haftar against the UN-backed government in the capital, Tripoli.
Sunday’s summit also aims to extract a pledge from foreign powers to honour a UN arms embargo and to halt any further interference in the conflict.
On Saturday, forces loyal to Gen Haftar blocked oil exports from major ports – a blow to the main source of income.
The meeting in the German capital, Berlin, will bring the two sides together, along with their foreign backers, the UN and other global powers, including Russia’s President Putin and Turkish President Recep Tayyip Erdogan.
Mr Erdogan, who has recently sent troops in support of the Tripoli government, said the talks would be “an important step” towards securing a ceasefire.
Libya has been wracked by conflict since the 2011 uprising which ousted long-time strongman Muammar Gaddafi.
Gen Haftar’s Libyan National Army (LNA) controls much of eastern Libya, and last April he launched an offensive against the country’s rival Government of National Accord (GNA) in the capital, Tripoli.
His forces have so far been unable to take the city, but earlier this month the LNA captured Libya’s country’s third-biggest city, Sirte.
According to the UN, the fighting has killed hundreds of people and displaced thousands more from their homes.
A truce was announced earlier this month between Gen Haftar and the GNA, led by Prime Minister Fayez al-Serraj.
But both sides blame each other for reported breaches of the agreement, and attempts to broker a lasting ceasefire broke down last week at a summit in Moscow.
The role of foreign powers
The role of foreign states in the conflict has come into focus in recent months, with Turkey passing a controversial law to deploy troops to help GNA forces in Tripoli.
Gen Haftar’s LNA has the backing of Russia, Egypt, Saudi Arabia, the United Arab Emirates (UAE), and Jordan.
On Saturday, UN Special Envoy to Libya Ghassan Salamé called on international powers to stop supporting local proxy groups with mercenaries, arms, financing, and direct military support.
He told BBC Radio 4’s Today programme that such actions created “a vicious circle where their proxies call for intervention in their fight, and their own ambitions bring more divisions.”
Mr Salamé told the BBC that a political solution to the conflict was best for all parties involved because Libya – with its vast geography, strong local identities, heavily-armed population and weakened government infrastructure – was a difficult country for one group to control.