| Caswell & Company Limited | Manufacturing | 1920 |
| Caswell Ventures Limited | Real estate | 1923 |
| Cat MAT IMB Ltd | Wholesale & retail | 2019 |
| Catalin Irimescu Ltd | Wholesale & retail | 2020 |
| Catalin Manole Ltd | Transport & logistics | 2016 |
| Catalyx UK Limited | Information & communication | 2013 |
| Catch 22 Baits Limited | Agriculture & fishing | 2015 |
| Cazactrans Ltd | Transport & logistics | 2021 |
| Cazu Choc's Ltd | Manufacturing | 2020 |
| CB Training (UK) Ltd | Professional & scientific | 2011 |
| Cbm-Logix Ltd | Information & communication | 2004 |
| CBN Locum Limited | Health & social care | 2023 |
| CC Corby Ltd | Wholesale & retail | 2026 |
| Ccinproperty Ltd | Real estate | 2026 |
| Ccpl Holdings Limited | Financial services | 2026 |
| Ccpl UK Limited | Financial services | 2021 |
| CDS UA Ltd | Construction | 2026 |
| Cebotari Ltd | Wholesale & retail | 2025 |
| Cedar Groove Ltd | Manufacturing | 2024 |
| Cedarwood Care and Support Ltd | Public administration | 2025 |
| Ceecee Green Ltd | Health & social care | 2019 |
| CEL Energy Solutions Limited | Construction | 2018 |
| Cellular Mouldings Limited | Manufacturing | 1994 |
| Central Point (UK) Ltd | Real estate | 2008 |
| CER Sports & Talent Group Limited | Administrative & support | 2026 |
| Cernei Group Ltd | Transport & logistics | 2025 |
| Certitudo UK Ltd | Administrative & support | 2022 |
| Cessa Events Ltd | Arts & recreation | 2023 |
| CF Holdings Limited | Manufacturing | 1996 |
| CG Steel Ltd | Construction | 2019 |
| CGC (Liverpool) Limited | Administrative & support | 2010 |
| Cgcarriers Ltd | Transport & logistics | 2026 |
| Cgle Haulage Limited | Transport & logistics | 2016 |
| CGT Square Consulting Limited | Information & communication | 2022 |
| CH Legal Consultancy Limited | Professional & scientific | 2015 |
| CH Plumbing and Heating Ltd | Construction | 2022 |
| Chambers Solutions Ltd | Manufacturing | 2025 |
| Charac Limited | Information & communication | 2020 |
| Charito Abordo Recruitment Limited | Administrative & support | 2023 |
| Charnwood Campus Management Limited | Administrative & support | 2014 |
| Charnwood Trustee One Limited | Administrative & support | 2015 |
| Charnwood Trustee Two Limited | Administrative & support | 2015 |
| Chashni UK Limited | Hospitality | 2019 |
| Chattha Builders Ltd | Construction | 2026 |
| Chauffeur 4 Hire Limited | Transport & logistics | 2023 |
| Checed Properties Limited | Real estate | 2025 |
| Checkley Property Solutions Ltd | Real estate | 2020 |
| Cheeky Monkees (Corby) Limited | Education | 2005 |
| Chelmsford City Land Limited | Real estate | 2026 |
| Chemence Graphics (Holdings) Limited | Manufacturing | 2014 |
| Chemence Graphics Nelson Limited | Manufacturing | 2012 |
| Chemence Graphics Pollington Limited | Manufacturing | 1984 |
| Chenee Jaro Recruitment Limited | Administrative & support | 2023 |
| Chestnut Edge (Stoke Albany) Management Company Limited | Households | 2023 |
| Chgams Ltd | Information & communication | 2023 |
| Chiado Limited | Information & communication | 2014 |
| Chico 10 Ltd | Wholesale & retail | 2024 |
| Chinez Ltd | Health & social care | 2019 |
| Chirila Auto Ltd | Wholesale & retail | 2025 |
| Chmi- Calvary Healing Ministries International Ltd | Other services | 2023 |
| Choice 888 Limited | Hospitality | 2024 |
| Choices Healthcare Services Limited | Public administration | 2025 |
| Chris Bonnello Ltd | Other services | 2025 |
| Chris Sloan Property Ltd | Real estate | 2016 |
| Christian & Ehizojie Limited | Health & social care | 2025 |
| Christianwalk Ministries Limited | Other services | 2003 |
| Chrome Nickel Alloys Limited | Wholesale & retail | 2008 |
| Chronoflux Systems Limited | Professional & scientific | 2024 |
| Cilt (UK) Services Limited | Professional & scientific | 2008 |
| Ciobanu Vladimir Ltd | Wholesale & retail | 2017 |
| CIP Delivery Limited | Wholesale & retail | 2022 |
| CIP Inspects Ltd | Wholesale & retail | 2024 |
| Ciprian Marius Ltd | Wholesale & retail | 2024 |
| Ciprian Solution Ltd | Transport & logistics | 2026 |
| Circa Props Limited | Construction | 1998 |
| Cirulis Transport Ltd | Transport & logistics | 2016 |
| Cissonius Developments Ltd | Hospitality | 2018 |
| Citizens Advice Services Corby & Kettering | Other services | 2007 |
| City Auction (Rockingham) Ltd | Wholesale & retail | 2014 |
| City Energy Limited | Construction | 2026 |
| City Fasteners Ltd | Wholesale & retail | 2015 |
| City Music Lessons Limited | Education | 2006 |
| City Music Limited | Financial services | 2014 |
| City Music Services Limited | Education | 2002 |
| Ciun Limited | Transport & logistics | 2025 |
| CJB Maintenance Services Ltd | Construction | 2025 |
| CJC Land and Developments Limited | Financial services | 2020 |
| Clansman Corby Ltd | Wholesale & retail | 2023 |
| Clark Partners Ltd | Financial services | 2012 |
| Clark Business Solutions Limited | Financial services | 2015 |
| Clarke Talbot Renewable Energy Ltd | Manufacturing | 2022 |
| Claudia Care Limited | Health & social care | 2022 |
| Claudiu & M Construction Ltd | Construction | 2021 |
| Claudius Vertesi Ltd. | Extraterritorial | 2017 |
| Claudiu’S Repairs Limited | Wholesale & retail | 2020 |
| Clauss Logistics Limited | Transport & logistics | 2019 |
| Clean and Safe Corby Limited | Wholesale & retail | 2016 |
| Clean Deeper Ltd | Administrative & support | 2020 |
| Clear Path Ahead Limited | Other services | 2024 |
| Cleavey Glass Limited | Wholesale & retail | 2021 |