If they do, Obama said, she will speak at their commencement next spring.
The first lady issued her challenge while joining GW students at a United We Serve volunteer event at a Habitat For Humanity site in Washington to help kick off the school's first Freshman Day of Service. She picked up a paint brush and helped paint a room.
"What's taking place at The George Washington University is what United We Serve is all about," Obama said. "My challenge to the GW community is to make service a daily part of their lives."
GW President Steven Knapp said he is confident everyone will rise to the challenge.
"Service is a core value of the George Washington community," he said.
More than 2,000 undergraduates contributed 60,000 hours of service during the 2008-2009 academic year.
The university's commencement will be May 16.