Ryan, 72, sat stone-faced as the verdict was read and afterward vowed to appeal.
"I believe this decision today is not in accordance with the kind of public service that I provided to the people of Illinois over 40 years, and needless to say I am disappointed in the outcome," Ryan said.
Ryan faces up to 20 years in prison for racketeering conspiracy charge alone, the most serious against him in the 22-count indictment. The jury also found him guilty of fraud, obstructing the Internal Revenue Service and lying to the FBI.
Co-defendant Larry Warner, a Chicago businessman and Ryan friend, was also found guilty of racketeering conspiracy, as well as mail fraud, attempted extortion, illegally structuring bank withdrawals and money laundering.
Neither man took the stand during their six-month trial.
Prosecutors accused Ryan of steering big-money state contracts and leases, including a $25 million IBM computer deal, to his friends and political insiders while he was secretary of state in the 1990s and then as governor starting in 1999.
In return for that help, he was rewarded with annual winter vacations in Jamaica, stays in Cancun and Palm Springs and gifts ranging from a golf bag to $145,000 in loans to his brother's business, prosecutors said.
Warner, 67, was one of those beneficiaries and raked in $3 million from Ryan-era deals, according to the office of U.S. Attorney Patrick Fitzgerald — who during the trial was also leading the federal investigation into the leak of CIA officer Valerie Plame's identity.
"There was just too much evidence, from too many witnesses, pointing too many fingers at Ryan and his colleague for either defense team to have been able to portray it as a coincidence or a witch hunt or anything short of widespread corruption," says CBS News legal analyst Andrew Cohen. "And that's why we see this verdict."
The case against the Ryan and Warner was the state's biggest political corruption trial in decades, and it had it share of troubles.
Late last month, six months of arguments and testimony nearly went down the drain when the judge discovered two jurors had failed to mention past arrests on their court questionnaires.