The signing took place at Campbell Street Bicycle Shop in suburban Arlington Heights.
Under the law, it is illegal for drivers to crowd or threaten bicyclists by driving too close to them.
The governor says the new law will also remind drivers to be alert for those riding on two wheels.
Governor Quinn said he wants "to make our state the number one state in the union when it comes to bicycling and having fun on a bicycle and participating and having trails that are well done all across Illinois."
A second piece of legislation will create a new 'Share the Road' license plate. Proceeds will go to fund education efforts.