The Bluejays won their seventh straight game while advancing to 13-1 for the season and to 2-0 in the Missouri Valley Conference.
Creighton's lead was cut to three with 55 seconds to play, but Austin Chatman, Doug McDermott and Grant Gibbs made two foul shots each to keep the Bluejays in front.
Gibbs scored 16 points and dealt out seven assist while McDermott had 15 and nine rebounds.
Illinois State (9-5, 0-2) was led by 15 points each from Bryant Allen and Tyler Brown. The Redbirds have lost two in a row after winning four consecutive games.