Absolutely shocking !
Two other states - Colorado and Maine - have removed Mr Trump from their primary ballots for violating a 14th Amendment "insurrection" clause.
The final outcome will likely be decided by the US Supreme Court.
Illinois' primary election is scheduled for 19 March.
Early voting in the primary has already begun. Mr Trump - the front-runner Republican presidential candidate - will remain on the ballot until at least Friday while he has time to appeal against the order.
Cook county circuit judge Tracie Porter agreed with voters who argued Mr Trump had violated the US constitution's 14th Amendment because of his role in the 6 January Capitol riot.
It comes after Colorado's Supreme Court barred Mr Trump from appearing on the Republican primary ballot in December, arguing Mr Trump's actions during the 2021 Capitol riot amounted to insurrection.
Related:
Maine: 2024-02-25 Maine's public schools purchased taxpayer-subsidized electric buses but say they are defective
Maine: 2024-02-22 Under Biden, the Number of Illegals Who Have Entered the U.S. is Greater Than the Population of 36 States
Maine: 2024-02-03 Trump trial delayed indefinitely in case stemming from Special Counsel Jack Smith's Jan. 6 investigation
Maine: 2024-02-25 Maine's public schools purchased taxpayer-subsidized electric buses but say they are defective
Maine: 2024-02-22 Under Biden, the Number of Illegals Who Have Entered the U.S. is Greater Than the Population of 36 States
Maine: 2024-02-03 Trump trial delayed indefinitely in case stemming from Special Counsel Jack Smith's Jan. 6 investigation