UN Secretary General Ban Ki-moon gathered over 60 heads of state and government with top NGOs at the summit, aiming to better keep conflicts from erupting and ensure legal retribution for those guilty of humanitarian crimes.
Celebrity stardust was sprinkled on the event by actors Daniel Craig and Forest Whitaker, who urged participants to seize a unique chance to make a difference for the world's worst off.
With some 60 million people displaced around the world and at least 125 million requiring assistance and protection in the biggest humanitarian crises since World War II, Ban said that the summit represented a chance to forge a "different future".
But the event has been shadowed by the boycott of medical charity Doctors Without Borders (MSF) and doubts that the two-day event can make any genuine impact.
"Let us seize this opportunity, let us make our mark as agents of change," said Ban.
He warned that realising the aims was not "an easy task" and required a "political will on a scale we have not seen in recent years."