Earl Krugel admitted his guilt in a plea deal after his co-defendant, Jewish Defence League chief Irv Rubin, died in an apparent suicide while awaiting trial in 2002.
Krugel, 62, admitted to conspiracy and weapons violations stemming from a plot to bomb the Los Angeles office of Representative Darrell Issa, a Republican from California, and the King Fahd mosque in Culver City. The plots were never carried out.
According to court documents, Krugel and Rubin said they targeted Issa because he is of Lebanese descent and they believed Arabs needed a "wake-up call".
Investigators said at the time there was no connection between the Jewish Defence League plot and the 11 September, 2001, attacks on New York and Washington.
"This is just not acceptable in the United States"
US District judge
Sentencing Krugel to the maximum term under the plea bargain, US District judge Ronald Lew said the crimes were "promoting hatred in the most vile way".
"This is just not acceptable in the United States," Lew said.
Krugel apologised in court for "all the sadness, pain and sorrow I've caused", saying that in his eagerness to make a political statement he had "embarked on a course that was wrong-headed, dangerous and illegal".
Krugel and Rubin were arrested in December 2001 on information supplied by an undercover informant who was shown a list of mosques and other potential targets and pipes with holes intended to be used as pipe bombs.
The Jewish Defence League was founded in 1968 by Rabbi Meir Kahane, who advocated the expulsion of all Arabs from Israel and the occupied territories. He was assassinated in New York in 1990.