Reporters swarmed Blagojevich as he walked out of his Chicago home and got into a car.
"I'm leaving with a heavy heart, a clear conscience and I have high, high hopes for the future," said Blagojevich, wearing a dark shirt, sport coat and blue jeans.
The 55-year-old married father will begin serving his term at the Federal Correctional Institution Englewood in suburban Denver. It's a low-security prison.
Blagojevich was convicted on 18 counts, including charges that he tried to sell or trade President Barack Obama's Senate seat.
The Colorado prison has a few other high-profile inmates, including Jeff Skilling, the former CEO and president of Enron who is serving a 24-year sentence for fraud and other crimes. But most of the facility's nearly 1,000 inmates are there for drug offences, and some could be in for violent crimes including murder, said U.S. Bureau of Prisons spokesman Chris Burke.
Inside, Blagojevich's life will be strictly regimented. The impeached governor - who was heard on the FBI wiretaps scoffing at the idea of earning a low six-figure salary - will work a menial prison job, possibly cleaning bathrooms or doing landscape work, starting at 12 cents an hour.
The Associated Press contributed to this report.