The judge sentenced DeLay to the three-year term on the conspiracy charge. He also sentenced him to five years in prison on the money laundering charge but allowed DeLay to accept 10 years of probation instead of more prison time.
The former Houston-area congressman had faced up to life in prison. His attorneys asked for probation.
During the sentencing hearing on Monday, prosecutors had only one witness-- a Texas businessman who leveled a number of allegations against DeLay.
But shortly after he began testifying, the judge cut him off and told prosecutors they could not prove the businessman's claims beyond a reasonable doubt.
DeLay's attorneys called on only one witness: former U.S. House Speaker Dennis Hastert.
Hastert testified that DeLay, once one of the most powerful men in U.S. politics, was not motivated by power but for a need to help others.
DeLay had argued that he didn't do anything illegal and that the charges were politically motivated.
The Associated Press contributed to this report.