A presidential memorandum issued Friday applies to Liberians who fled the country amid years of civil war and who are living in the United States under "deferred enforced departure status."
Their stay was to have expired on March 31, but Obama is directing the Department of Homeland Security to extend it by 18 months.
Large enclaves of Liberians live in states including Rhode Island, New York, Minnesota and the Carolinas.
U.S. Sen. Jack Reed, a Rhode Island Democrat, is praising the extension and says Liberians have become part of the "fabric of communities across the United States."