Sami Al-Arian admitted providing support to Islamic Jihad members as part of a plea-bargain deal agreed in April.
The former professor at the University of South Florida took the deal despite a jury last year failing to convict him on any of the 17 charges he faced - leading the judge in that case to order a mistrial.
The 48-year-old, born in Kuwait to a Palestinian family, admitted he helped Islamic Jihad members claim immigration benefits.
James Moody, a US district court judge, said al-Arian was a "master manipulator" and had lied about raising money for Palestinian charities.
Al-Arian told the Miami court he took responsibility for his actions and was grateful for the opportunities he received in the US, where he has lived for 30 years.
"As I leave, I harbour no bitterness or resentment," he said.
He has denied advocating violence and said he was being persecuted for his outspoken views on the Israeli-Palestinian conflict.
Islamic Jihad has claimed responsibility for a number of deadly suicide bombings in Israel and the Palestinian territories, including an attack in Tel Aviv last month that killed nine people.
Al-Arian is set to be released in eighteen months as he has already served three years and three months in prison.
The court also ordered he be deported from the US on his release.