The one-day meeting sponsored by the United Nations and Great Britain aims to allow representatives of the UN-backed authority to outline its priorities to rebuild the country's economy after five years of turbulence.
Fayez al-Sarraj, the head of the unity cabinet, arrived in Tripoli by sea with a naval escort nearly two weeks ago and has since won the support of key institutions that control Libya's wealth.
"We realise that popular support for the unity government... cannot last if we don't quickly manage to address urgent needs," said deputy prime minister-designate Moussa al-Kony.
"Basic services" such as health and electricity were priorities in addition to security, he said.
British diplomat Christian Turner, the foreign office's director general for the Middle East and Africa, said: "It is vital, of course, that the new Libyan government makes early progress on delivering tangible benefits to the Libyan people."
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"We are here today to talk about practicalities, to talk about support, and not just support that is political and diplomatic but to talk of concrete assistance.
"We will hear more on the presidency council's priorities for the Libyan people and we will be agreeing how we go about addressing those specific areas," Turner added.
Representatives from around 40 countries, as well as international organisations such as the European Union, Arab League, World Bank and International Monetary Fund, attended the meeting.
The offices of international organisations and many embassies working on Libya have been based in Tunis, awaiting better security in Tripoli where the unity government is working to establish its authority.
Libya has been in chaos since the 2011 uprising that ousted longtime ruler Moamer Kadhafi, dealing a blow to the country's economy and causing a liquidity crisis.
According to the World Health Organization, more than 2.4 million people in Libya out of a population of 6 million need humanitarian assistance.
The WHO has said that $50 million (around 44 million euros) is needed to meet the life-saving needs of nearly two million people in Libya's health sector alone.