List of Illinois companies
{{Short description|none}}
{{For|Illinois companies headquartered in the Chicago area|List of companies in the Chicago metropolitan area}}
{{Use mdy dates|date=April 2025}}
This is a list of Illinois companies which includes notable companies that are headquartered in Illinois, or were previously headquartered in Illinois. In general, this list does not include companies headquartered in one of the municipalities of the Chicago metropolitan area.
{{Horizontal TOC|nonum=y}}
Companies based in Illinois
=A=
=B=
=C=
=D=
=E=
=F=
=G=
- Gardner Denver
- GE Healthcare
- Glik's
- GlobalTap{{cite web|last=Popova|first=Maria|title=GlobalTap: A Sustainable Model for Drinking Water|url=http://bigthink.com/design-for-good/globaltap-a-sustainable-model-for-drinking-water|work=Design for Good|publisher=Big Think|accessdate=15 September 2013}}
- GoHealth
- Golub Capital
- Great Planes Model Manufacturing
- Greenlee
- Group O
- Growmark
- Groupon
- Grubhub
- GTCR
=H=
=I=
=J=
=K=
=L=
=M=
=N=
=O=
=P=
=Q=
=R=
=S=
=T=
- Testor Corporation
- Thoma Bravo
- Thomas Research Products{{cite news | url=https://www.bloomberg.com/apps/news?pid=newsarchive&sid=aK41bao18IEs | title=Hubbell Acquires Varon Lighting Group | work=Bloomberg | date=December 19, 2008 | accessdate=October 17, 2012}}
- Titan Tire Corporation
- Tower Hobbies
- Trend Is Dead! Records
- Tri-State Christian Television