The bill now awaits D.C. Mayor Vincent Gray's signature, who has voiced his support for the measure.
Dan Riffle, director of federal policies for the Marijuana Policy Project, said the council's vote is part of a growing national trend.
"This is a big step forward for our nation’s capital, as well as our nation as a whole," he said in a statement Tuesday. "Clearly, marijuana prohibition’s days are numbered in the United States."
Washington, D.C. joins 17 states that have also decriminalized marijuana in some form.
Congress has oversight over D.C. laws and can intervene to overturn measure, but is not expected to weigh in, according to CNN.