How To Look Up An LLC In Illinois? (A Complete Guide)

Published by Jon Morgan | Co-Founder & Chief Editor

Last updated: April 22, 2026

FACT CHECKED by Lou Viveros, Growth & Transition Advisor

Methodology
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Over the past 5 years, I've helped more than 40 clients look up, verify, and register LLCs in Illinois — catching name conflicts, lapsed registrations, and agent errors before they turned into legal headaches.

In this guide, I'll walk you through every reliable method to search Illinois LLC records, from the Secretary of State's database to trademark tools, so you can verify any business entity with confidence.

Quick Summary

How to Search an LLC in Illinois?

There's more than one way to search for an LLC in Illinois, and using just one method can leave gaps. The Secretary of State's website is your starting point, but it's not always the full picture.

With 5.5 million new business applications filed in 2023 alone, name conflicts are more common than most people expect — which is exactly why checking both state and federal databases matters [1].

You can also reach out to the state office directly by phone or email if you hit a dead end online.

Here are the methods to use when looking up an LLC in Illinois:

1. Use the Secretary of State's Website

The Illinois Secretary of State's website is your best first stop for searching business entities, including LLCs. I've used it dozens of times, and it's reliable — as long as you know how to work it.

Here's how to search for an LLC on the Illinois Secretary of State's website:

• Go to the Illinois Secretary of State's business entity search page.
• Choose the type of search you want to conduct. You can search by Business Name, Registered Agent, File Number, or use a Keyword.
• Enter your search criteria. If you're searching by business name, type in the full or partial name of the LLC you're looking for.
• If advanced search options are available — like filtering by position (President, Secretary, Manager) or using a partial word — use them to tighten your results.
• Review the list of matching entities. The results will show each company's file number, name, entity type, and status.
• Click the entity name to pull up the full record.

This platform allows for multiple search options:

a. Business Name

This option is the most straightforward way to find a business entity. You can enter the full or partial name of the business you seek.

The search results will list all entities that match or closely resemble the entered name, allowing you to review each entity's status, registration details, and other public information.

It's particularly useful for determining the availability of a business name for new registrations.

Follow these four rules when thinking of a new name:

1. Your LLC name must include "Limited Liability Company," "LLC," or "L.L.C." as a standalone designator
2. Your name cannot contain corporate terms like "Corp.," "Inc.," "Ltd.," or "Limited Partnership."
3. Your name must also be distinguishable from any existing LLC, corporation, or reserved name on file with the Secretary of State — sole proprietorships and trade names are excluded from this comparison.
4. If your LLC provides licensed professional services, the name must include "PLLC" or "P.L.L.C."

b. Registered Agent

Searching by the registered agent's name effectively finds all businesses associated with a particular agent.

This search can reveal the breadth of an agent's representation and is useful for legal professionals and businesses looking for information on their competitors' agents.

c. File Number

The file number is a unique identifier assigned to each business entity by the Secretary of State.

Searching by this number yields the most direct and specific information about a business, including its filing history, current status, and detailed entity information.

This method is highly accurate if you have specific documentation or references to a business entity.

d. Keyword

Keyword searches allow for a broader exploration of the business registry, which is useful for identifying companies within certain industries, locations, or with specific attributes in their names.

This method can help uncover trends, competitors, or potential partners by revealing a list of businesses with common keywords in their names or descriptions.

e. By Positions

• President: Identifies companies by searching for individuals holding the president position. This can provide insights into the leadership of various companies and is useful for networking, competitive analysis, or research purposes.
• Secretary: Searches based on the secretary's name can reveal the administrative backbone of companies, showing which entities share common secretarial support and potentially indicating corporate affiliations or networks.
• Manager: This search uncovers businesses associated with specific managers, offering a window into the management structures of various entities and how certain individuals are connected across the business landscape.

f. Partial Word

Partial word searches are particularly useful when the exact spelling of a business name is unknown or when trying to identify entities with similar names.

This approach can broaden the search results, providing a wider array of businesses that might meet the searcher's criteria. It is especially helpful for uncovering businesses with complex or commonly misspelled names.

2. Call the State

Sometimes the database doesn't give you everything you need. Calling the state directly is underrated — the business services team can answer specific questions and help you track down records that aren't obvious online.

Call 800-252-8980 (toll-free within Illinois) or 217-785-3000 if you're calling from outside the state.

3. Other Business Entity Search Alternatives

For a broader search, consider these alternatives:

1. Company Naming Services: Online tools that check whether a business name is available and registerable.
2. Trademark Searches: Confirm the name isn't already trademarked at the state or federal level.
3. Social Media Platforms: A quick way to find active businesses and see how they're operating publicly.
4. Search Engines: General searches can surface business activity, news mentions, and public records you won't find in a state database.
5. Domain Name Searches: Check whether the business name you want is already taken as a web domain.

How to Check If A Business Name Is Trademarked in Illinois

To check if a business name is trademarked in Illinois, you'll want to search two places: the U.S. Patent and Trademark Office's free search tool and the Illinois Secretary of State's Trademark Online Database.

Don't skip this step. The USPTO logged nearly 765,000 trademark applications in FY2024 — a 4% jump over FY2023 — and the federal register now has over 3.3 million active registrations [2]. The odds that someone's already using a name close to yours are higher than most people think.

And if you get it wrong, it's expensive. Trademark infringement disputes can cost small businesses anywhere from $50,000 to $250,000 or more in legal fees per case.

"Entrepreneurs in Illinois need to verify the trademark status of their business name before filing — not after. Catching a conflict early is a fraction of the cost of dealing with it later."

-Jon Morgan, Co-Editor & Co-Founder of Venture Smarter

Here's how to run a thorough trademark search:

1. Illinois Secretary of State's Trademark Online Database

The Illinois Secretary of State keeps a database of trademarks and service marks registered within the state. It's the right place to start if you're doing business primarily in Illinois.

To use the database:

• Go to the Illinois Secretary of State's official website and head to the Business Services section.
• Find the Trademark or Service Mark search function.
• Enter the name you want to check. You can search by mark name, owner name, or registration number.
• Review the results for any matches or similar names that could conflict with your intended business name.

2. U.S. Patent and Trademark Office's Free Search Tool

The USPTO's Trademark Electronic Search System (TESS) covers federally registered trademarks — which is what you need if you're planning to operate beyond Illinois.

To use TESS:

• Access TESS through the USPTO's official website.
• Run both a basic and advanced search using your proposed business name and relevant keywords.
• Look for identical or similar trademarks in your category. Pay close attention to the goods and services listed — a match in an unrelated industry is usually not a problem, but one in your space is.

3. Consider Hiring a Professional

For anything complicated — operating across state lines, international plans, or a name that's already close to an existing mark — a trademark attorney is worth the cost. I've seen founders spend thousands trying to fix a conflict that a $500 search would have caught upfront.

4. Check Domain Availability

Even if a name clears the trademark databases, the domain might already be taken. Check this early — it'll save you from building brand recognition around a name you can't own online.

5. Review Social Media and Online Presence

Run a quick search on the major platforms before you commit to a name. A business doesn't have to be formally registered to have built an audience under that name — and that can still create branding headaches down the road.

Reasons to Perform a Search

You can perform a search to:

• Ensure the desired LLC name is available for use.
• Avoid legal issues by ensuring the name isn't trademarked.
• Gather information about competitors in the market.
• Verify the status and legitimacy of potential business partners.
• Obtain contact information for networking or sales purposes.
• Check the history of legal disputes or compliance issues.
• Understand the business scope and activities of an LLC.
• Assess a business's financial health and stability before investing or engaging in transactions.

FAQs

References:

1. https://www.uschamber.com/small-business/new-business-applications-a-state-by-state-view
2. https://www.uspto.gov/dashboard/trademarks/