Pritzker signed the measures Wednesday afternoon at the Thompson Center in downtown Chicago. Dozens of lawmakers and other stakeholders applauded him as he arrived for the signing.
WATCH: Governor JB Pritzker speaks before signing budget, tax bills
Nine days after he celebrated the House passage of his Fair Tax plan, Pritzker signed it into law and set the stage for voters to approve in the state's constitution from a flat tax to graduated income tax.
"They will have an opportunity to vote to make sure that 97 percent of Illinoisans pay the same or less in income taxes and they will have a vote on eliminating the budget deficit, paying down our bills and reducing our pension liability," he said.
Opponents, including the group Ideas Illinois, launched a media campaign in the spring to try to block the vote, and will be stepping up that effort over the next 16 months to convince people to vote against the tax change.
"Voters understand that it will hurt job creators in the state and voters understand that the tax rates aren't permanent and once you take that cap off and the opportunity for them to change the rates very easily down the road," said Greg Baise, chairman of Ideas Illinois.
The theme of the campaign will be you can't trust Springfield politicians.
Supporters of the graduated income tax, including Pritzker-backed group Think Big Illinois, also plan their own media blitz.
"Our effort to restore firm fiscal footing for Illinois continues in November of 2020 when voters will have the power to say yes to a fair tax system that will improve the trajectory of our state's finances forever," he said.
If approved, the new scaled approach would take effect in January 2021.
Pritzker also signed the budget for the next fiscal year into law Wednesday.
The nearly $40 billion budget for the year that begins July 1, carrying a "balanced" stamp from both Republicans and Democrats, is a 2% increase over the current year. It fully funds the state's $9 billion pension contribution and authorizes the borrowing of $1.2 billion to pay $6.7 billion in overdue bills. The budget also includes a $1,600 annual pay raise for lawmakers and boosts education funding and money for the state's child welfare agency.
"Perhaps the greatest most unmitigated success is that we achieved something that has eluded state government for decades we passed a real balanced budget," Pritzker said.
There was pushback from some Republican lawmakers on the pay raise. The House surprised the Senate last week when it slipped the cost-of-living increase into the budget legislation and then didn't take action on the Senate's attempt to reverse it. GOP state Sen. Dale Righter of Mattoon said legislators shouldn't "try to slip it through in the last hours of session because that's what people resent."
House Republican Leader Jim Durkin released a statement, saying, "For two years in a row, Republicans and Democrats have proven that we can balance the state's budget with no new taxes on Illinois families. However, the graduated tax rates signed into law today are simply the next step to giving Illinois Democrats a blank check for uncontrolled spending for years to come. Illinois families should remain very wary on the rates that are being 'promised' today - as Democrats will continue to come back, year after year, and pickpocket more money from Illinois families and businesses."
The Associated Press contributed to this report.