The 29 largest companies in Rancho Cucamonga (2026 list)

#	Company	Industry	Headquarters	Employees	Founded
1	IEHP iehp.org A top 10 largest Medicaid health plan and the largest not-for-profit Medicare-Medicaid plan, providing quality, accessible, and wellness-based healthcare services	Hospitals and Health Care	🇺🇸 Rancho Cucamonga	2,054	1995
2	Chaffey College chaffey.edu A vocational and transfer-focused community college in western San Bernardino County, offering various programs, cultural experiences, and athletics opportunities	Higher Education	🇺🇸 Rancho Cucamonga	1,788	1883
3	Etiwanda School District etiwanda.org Primary/secondary education provider located in Rancho Cucamonga, CA, focused on serving students in the Etiwanda School District	Primary and Secondary Education	🇺🇸 Rancho Cucamonga	825	n/a
4	City of Rancho Cucamonga cityofrc.us Premier city in Southern California Inland Empire, offering a safe and desirable place to live, work, and play with award-winning architecture and community amenities	Government Administration	🇺🇸 Rancho Cucamonga	636	1977
5	Central School District csd.k12.ca.us Educational institution serving over 5,000 K-8 students in Rancho Cucamonga, with a focus on academic excellence and community engagement	Primary and Secondary Education	🇺🇸 Rancho Cucamonga	487	n/a
6	Amphastar Pharmaceuticals, Inc.amphastar.com A pharmaceutical company with cGMP-compliant facilities developing, manufacturing, and marketing biopharmaceutical products globally, focusing on high-quality production in the United States	Pharmaceutical Manufacturing	🇺🇸 Rancho Cucamonga	423	1996
7	Realty Masters rmarealty.com This company offers real estate agents 100% commissions, professional resources, and support without hidden fees to empower agents to succeed	Real Estate	🇺🇸 Rancho Cucamonga	416	2005
8	National Community Renaissance nationalcore.org This company provides award-winning affordable housing and social services to help families achieve self-sufficiency and homeownership, transforming lives and communities	Real Estate	🇺🇸 Rancho Cucamonga	374	1992
9	Aspire General Insurance aspiregeneral.com A California-based insurance company specializing in private passenger auto coverage, with expertise in liability, physical damage, and claims handling	Insurance	🇺🇸 Rancho Cucamonga	365	2013
10	New-Indy Containerboard LLC newindycontainerboard.com A leading manufacturer of recycled containerboard using 100% recycled fiber, supplying to the corrugated box industry with environmentally conscious processes and sustainable solutions	Paper and Forest Product Manufacturing	🇺🇸 Rancho Cucamonga	341	2012
11	Bradshaw Home bradshawhome.com A leading marketer of kitchenware, cleaning products, and tools Manufacturer and distributor of well-known brands and private label products in North America Acquisition of Casabella brand in 2017	Manufacturing	🇺🇸 Rancho Cucamonga	329	1969
12	TRL Systems, Inc.trlsystems.com Integrated fire life safety and security solutions provider, offering in-house created products, quick turnaround, expert service team, and personalized support for businesses	Construction	🇺🇸 Rancho Cucamonga	246	1981
13	Nongshim America, Inc.nongshimusa.com This company specializes in producing ramyun and bowl noodles with a total production capacity of 200 million units per year They actively sponsor food shows and events in the US, Canada, Mexico, and South America	Food and Beverage Manufacturing	🇺🇸 Rancho Cucamonga	233	1994
14	Dunlop Tires North America, Inc.paycomonline.net A subsidiary of Sumitomo Rubber Industries, Falken Tires and Dunlop Motorcycle Tires manufacture high-performance tires for cars, trucks, and motorcycles globally	Motor Vehicle Manufacturing	🇺🇸 Rancho Cucamonga	213	1888
15	Certerra RMA Group rmagroupinc.com Client-centered geotechnical engineering and materials testing firm with multiple California offices Specializes in services like geotechnical engineering, pavement engineering, and environmental engineering	Civil Engineering	🇺🇸 Rancho Cucamonga	184	1962
16	Falken Tire falkentire.com Global manufacturer specializing in high-performance tires for cars, trucks, SUVs, with strong motorsports heritage and innovative product quality.	Motor Vehicle Manufacturing	🇺🇸 Rancho Cucamonga	182	1983
17	Adriana's adrianasinsurance.com A company with 30+ years of experience and 60+ offices in Southern California offering insurance services for auto, home, life, business, and motorcycle They also provide services for plate renewal, title transfers, and international licenses	Insurance	🇺🇸 Rancho Cucamonga	177	1990
18	VEVOR vevor.com Supplier of premium quality power tools, automotive equipment, material handling products, and restaurant/food service supplies with lowest prices and worry-free shopping experience Operating in 40+ global warehouses	Retail	🇺🇸 Rancho Cucamonga	172	2007
19	PAR Western Line Contractors, LLC parwlc.com A leading provider of outside infrastructure construction services, specializing in electrical, gas, and telecom projects with a focus on safety and innovation	Construction	🇺🇸 Rancho Cucamonga	171	n/a
20	Ameron International nov.com A global supplier of concrete and steel pipe systems for water and wastewater conveyance, energy and transportation markets, and PVC sheet linings for corrosion protection	Utilities	🇺🇸 Rancho Cucamonga	163	1907
21	Evolution Fresh evolutionfresh.com This company offers cold-pressed juices using high pressure processing to provide nutritious and delicious options in grocery stores and select Starbucks® locations	Food and Beverage Services	🇺🇸 Rancho Cucamonga	160	n/a
22	Klatch Coffee, Inc.klatchcoffee.com A nationally recognized micro coffee roaster based in Southern California, known for award-winning espressos, coffees, and barista training since 1993	Food and Beverage Services	🇺🇸 Rancho Cucamonga	87	1993
23	Mindrum mindrum.com This company manufactures specialized components and assemblies from difficult and exotic materials, employing advanced machining, grinding, and assembly techniques for various industries.	Defense and Space Manufacturing	🇺🇸 Rancho Cucamonga	36	1956
24	Paramount Machine Company, Inc.paramountmachine.com A leader in precision manufacturing serving industries such as Aerospace, Defense, Medical, Electronics, and Commercial with a focus on quality and customer service	Aviation and Aerospace Component Manufacturing	🇺🇸 Rancho Cucamonga	21	1964
25	D & R Glass, Inc.drglassinc.com Providing comprehensive glass solutions from design to installation for contractors, architects, and owners with a focus on quality, attention to detail, and customer satisfaction	Wholesale Building Materials	🇺🇸 Rancho Cucamonga	19	1984
26	King Diamond Tools n A global manufacturer of high-quality diamond cutting tools trusted by top US retailers, with a team of skilled engineers and state-of-the-art machinery	Manufacturing	🇺🇸 Rancho Cucamonga	13	1993
27	SI Testing sitesting.net Provider of electrical power services and solutions in the US, specializing in testing, servicing, and repairing electrical equipment to ensure reliability and safety for clients	Appliances, Electrical, and Electronics Manufacturing	🇺🇸 Rancho Cucamonga	12	2015
28	DoWell Dental Products, Inc.dowelldentalproducts.com Innovative manufacturer of surgical equipment for dental professionals, offering a wide range of products at competitive prices with fast delivery	Medical Equipment Manufacturing	🇺🇸 Rancho Cucamonga	9	2006
29	The Kitchen Post, Inc kitchenpost.com Specializing in kitchen and bathroom remodeling, The Kitchen Post offers custom cabinetry, countertops, moldings, hardware, windows, flooring, and more	Construction	🇺🇸 Rancho Cucamonga	7	2002

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How this list is built

Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Oct 24, 2026.

The same list elsewhere in United States

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The largest companies in New York State 10,485
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The largest companies in Chicago 1,668