That's nearly double the 50,000 they originally expected to sign up.
All Kids officially started July 1 and is the nation's first program to guarantee insurance for all Illinois children.
A spokeswoman for the state Department of Healthcare and Family Services says so far about 45,000 kids have signed up.
That includes 40,000 who already qualified for state coverage but hadn't signed up and 5,000 kids who didn't qualify until All Kids was created.
The state insists it will be able to cover all the enrollees with the $45 million budgeted by lawmakers.
Rep. Gary Hannig of Litchfield says the higher numbers are good news but also put more pressure on the state to make sure there's enough money to cover the increase.