The Senate voted 38 in favor, 17 opposed. Two senators voted present and two were no votes.
WATCH: Sen. Steans makes final statement, Senate votes on marijuana bill
"I stand comfortably here saying to you that this is the largest, most equity-centered bill with the most criminal justice reform in one piece of legislation in the country right now, and the world is watching," said Senator Toi Hutchinson (D-Olympia Fields).
The bill, which was amended by the Senate, now goes back to the Illinois House, which indicated in social media posts it would take action on it quickly. The General Assembly is scheduled to adjourn Friday.
Years of backroom discussion moved to a full floor debate in Springfield Wednesday evening about the merits and dangers of making marijuana fully legal to adults in Illinois.
"The simple fact is the stats demonstrate that if we do this more people will use cannabis," said Senator Dale Righter (R-Mattoon). "That's a fact."
"While the usage of cannabis has been the same across all racial groups, the actual incarceration charges have been shown to be seven times more likely for people of color than Caucasians," said Sen. Heather Steans (D-Chicago). "This bill is going to set the model, I believe, the gold standard, for how to approach social equity issues related to cannabis legalization."
Under HB 1438 adults 21 and older could legally buy marijuana from licensed dispensaries and could possess up to one ounce (28 to 30 grams). The Executive Committee approved the plan 13-3 on Wednesday.
The bill gives local jurisdictions the opportunity to opt out or put restrictions on dispensaries, and mandates packaging of pot be sealed and labeled.
If passed, recreational marijuana would be legalized effective on January 1, 2020.
Steans has garnered some Republican support in her quest for Illinois to join 10 other states in allowing recreational use.
She appeased law enforcement by changing the legislation to limit homegrown pot to qualified medical-marijuana patients and has tightened a provision that allows people with past convictions of possession of 30 grams to one pound (500 grams) to get those records expunged.
The differences in home grow regulations reflect how states view the competing arguments about home cultivation: Opponents say it fuels the black market sale of the drug while proponents argue that if businesses can sell it, they should be able to grow it.
"We don't say anywhere in this country that people aren't allowed to have a small craft brew at their house if they want to, and I think the same rules should apply here," said Kris Krane, president the Phoenix-based cannabis business 4Front Ventures.
She acknowledged that the change is a concession to law enforcement in order to win approval for the measure, but she noted that many lawmakers have concerns about product safety, as well as illegal sales.
"One of the reasons we're going to tax-and-regulate is to make sure you're not getting product that's got issues," Steans said. "By limiting that (home grow) significantly, you reduce the problems."
If signed into law, legal marijuana expected to generate tens of millions of dollars in tax revenue. Governor JB Pritzker said during his campaign that he would sign the bill.
The Associated Press contributed to this report.