On Friday, Keller, a real estate agent, told US District Judge Richard Leon he knew his actions were wrong.
“I have no excuse for why I am in front of you today,” he was quoted as saying by the Associated Press.
“I understand my actions were criminal and that I am fully responsible for my conduct.”
Judge Leon said he believed Keller should help speak to young people about his mistakes, rather than spend time in jail.
“If there ever was a case that screams out for probation, this is it,” the judge said.
He also ordered Keller to perform 360 hours of community service.
In total, he won five medals – including two golds – at three Olympic games, but had personal and financial difficulties after withdrawing from competitive swimming.
About 1,200 people have so far been charged over the Capitol riot, of which about 900 have pleaded guilty or been convicted.
Sentences have ranged from just days in jail to 22 years in prison.
