As of October 20, 2026, ListRiver's records show 5,856 active registered businesses in Oak Brook, Illinois, the 26th most among Illinois cities. 62% are LLCs. 49 were formed in September 2026. That is 1% of all Illinois businesses on record.
How many businesses are registered in Oak Brook, Illinois?
ListRiver has 5,856 active registered businesses in Oak Brook, Illinois on record as of October 20, 2026, from official Illinois business registry data. Dissolved and defunct businesses are not counted.
How many new businesses were formed in Oak Brook, Illinois in September 2026?
49 businesses on record in Oak Brook, Illinois were formed in September 2026.
How many new businesses opened in Oak Brook, Illinois in the last 12 months?
512 businesses on record in Oak Brook, Illinois were formed in the 12 months through September 2026.
What is the most common type of business in Oak Brook, Illinois?
LLCs are the most common: 3,659 of 5,856 businesses on record (62%), followed by Corporations with 1,800 (31%).
Where does this data come from?
From Illinois's official business registry. ListRiver loads each new state file, standardizes it, removes duplicates and updates its database weekly. Email and industry details are added from SMBCredit.net where available.
How do I get a list of businesses in Oak Brook, Illinois?
Use ListRiver's list builder to filter Oak Brook, Illinois businesses by entity type, formation date, industry and contact details, see the exact count and price, and download a CSV. Every list includes monthly refresh files.
Free to use on any site, and it updates itself every month. Copy this code and paste it into your page. Preview the chart.
Counts come from official Illinois business registry records on file with ListRiver, current as of October 20, 2026. They include businesses that are active on the state register; dissolved and defunct entities are excluded. Contact details are added from SMBCredit.net where available. Formation months reflect the registration date the state reports. See the methodology for sources, update schedules and known limits.