The wage history law bars employers from asking job applicants how much they made in previous jobs.
"Change won't come overnight but it will come sooner because of what we do here today," Gov. Pritzker said before signing the bill.
Supporters of the Equal Pay Act say it's designed to close the wage gap between men and women.
"In Illinois we know women get the job done and it's time to pay them accordingly," Gov. Pritzker said.
The governor's signing ceremony takes place at 12:30 p.m. at the Chicago Women's Park and Garden.