Jackson had pleaded guilty in February for using campaign money to buy personal items, including a $43,350 gold-plated Rolex watch.
U.S. District Court Judge Amy Berman Jackson said that as a public official Jackson was expected to "live up to a higher standard of ethics and integrity."
Jackson, 48, the son of civil rights leader Jesse Jackson, had been a Democratic congressman from Illinois from 1995 until he resigned last November.
Under the plea deal, Jackson could have been sentenced to nearly five years in prison.
Jackson's wife, Sandra Jackson, has been sentenced to one year in prison for filing joint federal income tax returns that understated the couple's income. She spent $5,150 in campaign funds on fur capes and parkas, according to court documents.
Jackson said earlier Wednesday that he hoped his wife would get probation and that if that wasn't available, he would want to serve her sentence for her.
"Give me her time," he said.
The Associated Press contributed to this report.