U.S. District Court Chief Judge Michael Davis sentenced Abdifatah Yusuf Isse, Salah Osman Ahmed and Ahmed Hussein Mahamud each to 36 months in federal prison. Omer Abdi Mohamed was sentenced to 144 months in prison.
The three men given 36-month terms testified against Mahamud Said Omar, who was sentenced this week to 20 years in prison for "numerous" offenses related to his support for al-Shabaab.
Omar was convicted for funneling money to al-Shabaab and for assisting with the travel of men from Minnesota to Somalia to join al-Shabaab.
FBI officials said the sentencing serves as a reminder that national security in the United States remains focused on efforts to thwart radicalization.
U.S. Attorney B. Todd Jones said the sentences "reflect not only the misguided and insidious nature of their crimes but also the importance of cooperation and community involvement in preventing potential acts of terrorism."
The sentences were part of a federal investigation dubbed Operation Rhino. It focused on the recruitment of about 20 ethnic Somalis from Minneapolis who were sent to fight with al-Shabaab, an affiliate of al-Qaida. The U.S. Department of Justice said some recruits left for Somalia in 2007.