Trump told reporters at Joint Base Andrews that Blagojevich "served eight years in jail. It's a long time to go."
Blagojevich was housed at Englewood Federal Correctional Institution in Jefferson County.
Trump publicly hinted he would use his clemency powers for Blagojevich, a Democrat, in August. But he faced sharp blowback from some conservative members of Congress, including from Illinois, as well as from some White House advisers who said it wouldn't play well.
Internally, the effort to pardon or commute Blagojevich's sentence was championed by Jared Kushner, who has led the administration's criminal justice reform efforts.
Blagojevich appeared on Trump's boardroom reality show NBC's "Celebrity Apprentice" in 2010 but was fired by the future president before the final round.
Several Republican lawmakers aired their concerns in phone calls to acting White House chief of staff Mick Mulvaney and White House counsel Pat Cipollone. Two Republicans, Reps. Darin LaHood and Mike Bost, directly appealed to Trump not to use his clemency powers for Blagojevich.
By August, the White House had already been working for several months on vetting Blagojevich's case. The President first raised it in 2018.
Trump has suggested in his public comments about the case that he believes Blagojevich was simply doing what all politicians do.
"I would think that there have been many politicians -- I'm not one of them, by the way -- that have said a lot worse over the telephone," he said last year.
The Federal Bureau of Prisons said Tuesday night that Blagojevich had left the Jefferson County facility.
It is unclear exactly when he departed the prison. However, he briefly spoke to reporters at Denver International Airport about 7:30 p.m. Tuesday while waiting for his flight to Chicago.
"I think it's appropriate to express my deepest and most profound and everlasting gratitude to President Trump. He didn't have to do this. He's a Republican president. I was a Democratic governor. And my fellow Democrats haven't exactly been very nice to him. So I'm very grateful to him and I'll have a lot more to say tomorrow," Blagojevich said.
FOX31's Shaul Turner was the only Denver reporter to interview the former governor at DIA. She asked him if he had any political goals.
"When you've been in a place like I've been at for the last eight years, you kind of take one day at a time. You don't think too far ahead because you don't know what tomorrow's going to bring," he said.
Blagojevich said he learned a lot while incarcerated.
"I've learned a lot about our criminal justice system and how wrong and how unfair it can be -- how cruel it can be. I learned about how it disproportionately discriminates against people of color," he said, adding that the experience has brought him closer to God.
A news conference is scheduled in Chicago at 10 a.m. Mountain Time.