His two co-defendants in the case, Adham Hassoun and Kifah Jayyousi, were given lesser sentences of 15 years and eight months and 12 years and eight months, respectively.
The sentences imposed by U.S. District Judge Marcia Cooke fell far short of the government prosecutors' previous request of life in prison for all three defendants.
Following a trial that last nearly four months, a jury found all three men guilty of conspiring to kill and kidnap people overseas.
Defense attorneys, however, said the three were in fact working to aid Muslims in countries like Bosnia and Chechnya who were the victims of war. Lawyers for Hassoun said they would file an appeal within 10 days.