The rejection came without comment.
A group called Choose Life Illinois Inc., which supports adoption and fights abortion, wanted the state to issue the anti-abortion vehicle plates, the Los Angeles Times reported, and went to court to force Illinois to comply.
But the state refused, with officials saying the state should not take a position on abortion, even though the group had 25,000 signatures on a petition asking for the right to get the plates in Illinois.
A federal appeals court in Chicago ruled for the state last year, and the group asked the U.S. Supreme Court for review, citing free speech guarantees and claiming discrimination.
The Times said the effort to offer "choose life" plates has been successful nationally, with 24 states offering the plates and efforts in 14 more to get approval.