Trump announced his decision to reporters as he arrived at Joint Base Andrews in Maryland en route to Los Angeles.
"Yes, we commuted the sentence of Rod Blagojevich," Trump said. "He served eight years in jail, a long time. He seems like a very nice person, don't know him.
"He'll be able to go back home with his family after serving eight years in jail, that was a tremendously powerful, ridiculous sentence in my opinion."
Illinois' governor from 2003 to 2009, Blagojevich was impeached from office for various acts of corruption, including the "auctioning off" of President Barack Obama's Illinois Senate seat following his 2008 election and attempting to extort former Chicago Mayor Rahm Emanuel.
An appeals court dismissed five of Blagojevich's 18 convictions -- wire fraud, conspiracy to commit extortion, attempted extortion and conspiracy to commit bribery -- in 2015. Despite the reduction in charges, a federal court handed down the same sentence -- 14 years -- in 2016.
In addition to Blagojevich, Trump commuted the sentences of Tynice Nichole Hall, Crystal Munoz and Judith Negron, who was serving a 35-year sentence for Medicare fraud.
He also handed down a number of pardons, including for former San Francisco 49ers owner Edward DeBartolo Jr., Michael Milken (imprisoned for securities-related felonies); Ariel Friedler; former New York City Police Commissioner Bernard Kerik (who served four years for tax evasion); Paul Pogue; former General Services Administration official David Safavian (imprisoned in connection to the Jack Abramoff scandal); and Angela Stanton.