"It's an overused phrase I know, but I trust you know its genuine today, I am humbled. I'm trembling and I like it," Penn said after accepting the 2012 Peace Summit Award from former Soviet President Mikhail Gorbachev, who was joined on stage by the Dalai Lama and former Polish President Lech Walesa.
Penn has become a major player in efforts to rebuild Haiti after the January 2010 earthquake that devastated the island nation, flattening thousands of buildings, killing more than 300,000 people and leaving at least 1.5 million homeless.
He used his speech at the 12th World Summit of Nobel Peace Laureates to urge the world community to remember Haiti and invest in the country's future and President Michel Martelly, who took office in May 2011.
"We have a very short window to support this team of the Haitian people's choosing," Penn said. "We have four years to solidify the seating of institutions that can sustain democratic solutions."
Papers in Penn's hands shook and he became emotional at times during his speech as he described conditions in Haitian refugee camps or told the story of a Haitian police officer who lost his family in the earthquake. Penn also warned that if Haiti fails it could become a harbor for narcotics trafficking and terrorism near the United States.
Penn is the first non-Haitian to be designated an ambassador-at-large for Martelly. The actor is CEO of the J/P Haitian Relief Organization, a rapidly growing and increasingly prominent aid group. The organization manages two camps that are home to about 18,000 people.
Penn spends at least half his time in Haiti.
"He actually exchanged his home in Malibu for a tent," Udo Janz, United Nations high Commissioner for Refugees, said when he introduced Penn to accept the award. "Think of it as the Oscar for your humanitarian commitment Sean."
Penn won his first Academy Award for Best Actor in 2003 for "Mystic River" and his second in 2009 for "Milk."
At the last panel of the summit, the Nobel Peace laureates had strong opinions about the need for global cooperation in other areas: to draw down weaponry and focus more resources and energy on humanitarian needs.
"I believe that we really have to strive for demilitarization, which we should stop thinking is a dirty word," said Prof. Jody Williams, Nobel Peace Laureate 1997.
Former Soviet President Mikhail Gorbachev said through an interpreter that a new world order that was more stable and more humane was needed.
The Dalai Lama joined fellow peace laureates for the first time at the summit Wednesday. "Many have different interests, and quite often the reaction is use of force," he said.
Some of the summit attendees were students and some watched the discussions online. Laureates focused many of their comments at young people and encourage a new generation of human rights defenders to stand up to bullies, speak out against injustice and organize for peace.
The gathering was the first world summit of Nobel Peace laureates in North America.
The Associated Press contributed to this report.