Walli Mujahidh, 34, Frederick Domingue Jr., formerly of Los Angeles, and Abu Khalid Abdul-Latif, born Joseph Anthony Davis, 35, were convicted of scheming in 2011 to attack the recruiting facility with automatic rifles and grenades, the Los Angeles Times reported.
Abdul-Latif, a bankrupt Washington state janitor, was given an 18-year prison term two weeks ago.
The U.S. Justice Department said in a release U.S. District Judge James L. Robart said the plot "could have done incredible harm if it had gone forward," the Times said.
"This defendant planned to attack a military center when there would be the largest possible gathering of new recruits and their families," U.S. Attorney Jenny A. Durkan said in a statement. "He targeted young men and women solely because they wanted to serve our country. His goal: to inspire others with a message of hate."
Mujahidh said in a statement before sentencing he was "highly remorseful" for his "cowardly and shameful" actions.
"I would like to apologize to my country for my betrayal, the employees, staff at the military entrance processing station for any harm I might have caused any of them," Mujahidh said. "I would also like to apologize to my religion for any misrepresentation I might have caused. As well as my family for any shame I might have brought upon my name."