UNRWA chief Pierre Kraehenbuehl said the funding would allow the agency, which provides education and health services to Palestinians, to cover costs for the coming months and avoid a budget crisis.
Around 35 countries took part in the conference, mostly European and Arab nations, with the biggest contributions coming from the EU, Germany and Britain.
The conference was held on the same day as President Donald Trump's administration unveiled the economic component of a long-awaited Middle East peace plan, at a workshop in Bahrain boycotted by the Palestinian Authority.
The US plan dangles the prospect of $50 billion of investment in the Palestinian territories and neighboring Arab countries over 10 years.
Last year, the Trump administration cut all funding to UNRWA, arguing that it was flawed as Washington pressed ahead with work on proposals for an Israeli-Palestinian solution.
US Middle East advisor Jason Greenblatt in May told the Security Council that the agency should be dismantled and its services handed over to countries hosting the Palestinian refugees and NGOs.
Kraehenbuehl welcomed the pledge of $110 million, saying it was an "important amount" but said UNRWA would be seeking more funding to cover its annual budget of $1.2 billion in September.
"We hope this allows us to bridge a lot of the needs that we have in the next three to four months," he told reporters.
There were no announcements of new contributions from Gulf countries, but the UNRWA chief stressed there were strong expressions of support for the agency's work.
Last year, UNRWA relied on extra money from member states and internal savings to cover a $446 million budgetary hole. This year it unveiled a budget of $1.2 billion, unchanged from 2018.
Founded in 1949, UNRWA runs schools and provides health care for some five million Palestinian refugees in Jordan, Lebanon, Syria, the West Bank, and the Gaza Strip.
Israel and the United States do not like the fact that Palestinian refugees can pass on refugee status to their children and want to reduce the number of people receiving aid from UNRWA. The Palestinians say this violates their rights.
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