Filing an appeal
The former governor sat with hunched shoulders while waiting for the verdict. Afterward he told assembled reporters he intended to file an appeal.
"I didn't do anything wrong, I didn't break any law," Blagojevich said.
"Notwithstanding the fact that the federal government threw everything at me including the kitchen sink, in every count except for one they were unable to prove I did anything wrong."
Blagojevich, a Democrat ousted from office last year during his second term by the state legislature, faces a potential prison term of five years and a fine of up to $250,000 on the single guilty count.
The verdict on Blagojevich, 53, was delivered after 14 days of deliberations.
Prosecutors said he and his aides operated the state as a money machine by wringing campaign donations out of people doing business with the state.
His defence lawyers portrayed him as a talkative bumbler who was given bad advice but never received any illegal funds.
In a surprise decision during the trial, Blagojevich opted not to testify even after months of loudly declaring that he would take the stand in his own defence.
Obama and some senior White House staffers played a peripheral role in the case, which was built on FBI wiretaps.
In one tape heard by the jury, Blagojevich cursed that Obama had not offered him a Cabinet post or anything else in exchange for what Blagojevich judged as making a favoured appointment to the vacant senate seat.
The profanity-laced tapes made the one-time congressman and his wife Patti the object of television talk-show comedy bits. In the months leading up to the trial, the couple each made appearances on interview and "reality" shows.
Blagojevich was arrested in December 2008, two months after Obama won the White House race, vacating one of the two Illinois seats in the US senate.
Blagojevich, who ultimately named fellow Democrat and state attorney-general Roland Burris to the seat, was impeached by the Illinois state legislature in January 2009 for corruption and misconduct. He was kicked out of office shortly thereafter.
The affair has again shone the spotlight on Chicago's corruption-tainted political scene, but Obama and his administration have managed to escape the scandal unsullied.
Five of the past nine Illinois governors have been indicted or arrested for fraud or bribery and Blagojevich's predecessor, Republican George Ryan, is serving a six-and-a-half year jail term for fraud and racketeering.