| Cooltherm Air Conditioning Ltd | Construction | 2022 |
| Cooper Beard Estate Agency (Rushden) Limited | Real estate | 2001 |
| Cooperostlund Limited | Manufacturing | 2006 |
| Coopers IFA Limited | Professional & scientific | 2011 |
| Coopers Project Management Limited | Professional & scientific | 2024 |
| Coots and Boots Holdings Ltd | Professional & scientific | 2026 |
| Copal Ltd | Hospitality | 2021 |
| Cope Investments Limited | Real estate | 2024 |
| Copiers@Cost Limited | Extraterritorial | 2015 |
| Copley Site Services Limited | Construction | 2011 |
| Copper Learning Ltd | Education | 2023 |
| Copperhouse Court Management Company Limited | Administrative & support | 2005 |
| Copperwood Compliance Ltd | Public administration | 2024 |
| Coppice 1962 Limited | Extraterritorial | 2015 |
| Coppola Export Ltd | Wholesale & retail | 2024 |
| Copsem Lane Woodland Limited | Agriculture & fishing | 2014 |
| Copsewood Resource Management Ltd. | Financial services | 2025 |
| Copy & IT Ltd | Administrative & support | 2026 |
| COR Transport Ltd | Transport & logistics | 2018 |
| Cora Homes Limited | Construction | 2009 |
| Cora Social Media Limited | Administrative & support | 2025 |
| Coral Property Estates Limited | Real estate | 2012 |
| Coraltrend Limited | Hospitality | 1986 |
| Coraz Ltd | Transport & logistics | 2019 |
| Corbel Technology Ltd | Information & communication | 2026 |
| Corben Construction LLP | | 2011 |
| Corbiere Inns Ltd | Hospitality | 2006 |
| Corby Cube Theatre Trust | Arts & recreation | 2010 |
| Corby Hire Solutions Limited | Construction | 2020 |
| Corby Management Company Limited | Households | 2005 |
| Corby Windscreens Limited | Wholesale & retail | 2007 |
| Cordialventuresolutions Limited | Households | 2025 |
| Core & Co Reformer Pilates Ltd | Arts & recreation | 2023 |
| Core BIO Energy Ltd | Extraterritorial | 2014 |
| Core Collective Pilates Ltd | Arts & recreation | 2025 |
| Core Onyx Ltd | Wholesale & retail | 2025 |
| Core Strategic Consultancy Limited | Professional & scientific | 2025 |
| Coreecartt Ltd | Wholesale & retail | 2026 |
| Corex Minerals Ltd | Manufacturing | 2013 |
| Corganiser Ltd | Administrative & support | 2026 |
| Cori Providing Services Ltd | Administrative & support | 2025 |
| Corkers Limited | Extraterritorial | 2026 |
| Corkerz Guardianship Ltd | Education | 2009 |
| Corley Cycles Ltd | Wholesale & retail | 2012 |
| Cornel-Dragos Ltd | Transport & logistics | 2026 |
| Corneliu's Logistic Ltd | Transport & logistics | 2020 |
| Corner Shop Northampton Ltd | Wholesale & retail | 2018 |
| Cornerstone Merchant Services (North) Limited | Administrative & support | 2010 |
| Cornerstone Winner Limited | Health & social care | 2023 |
| Cornhill Management (Pattishall) Company Limited | Real estate | 2020 |
| Cornovan Limited | Transport & logistics | 2019 |
| Corporate Accounting Systems Ltd | Professional & scientific | 2017 |
| Corporate Service Solutions Limited | Wholesale & retail | 2002 |
| Corporate Smarts Ltd | Professional & scientific | 2020 |
| Correx Limited | Other services | 2003 |
| Corroboro Limited | Financial services | 2021 |
| Corti Trans Ltd | Transport & logistics | 2023 |
| Corveyus Ltd | Professional & scientific | 2019 |
| Coryton 10 Renewables Limited | Professional & scientific | 2023 |
| Cosenia Ltd | Administrative & support | 2021 |
| Cosford Solutions Limited | Wholesale & retail | 2012 |
| Cosmetic Auto Fleet Repairs Ltd | Wholesale & retail | 2021 |
| Cosmetic Hair Extensions and Plus Limited | Health & social care | 2016 |
| Cosmeticplus Limited | Health & social care | 2006 |
| Cosmin Inc Limited | Construction | 2017 |
| Cosplayworld Ltd | Wholesale & retail | 2021 |
| Cost Consulting Ltd | Professional & scientific | 2015 |
| Costa & IRI Ltd | Transport & logistics | 2019 |
| Costamar Limited | Transport & logistics | 2015 |
| Costelg Ltd | Transport & logistics | 2022 |
| Costessey Energy Limited | Energy | 1997 |
| Costin Spedition Ltd | Transport & logistics | 2017 |
| Costy Haulage Ltd | Transport & logistics | 2022 |
| Cosworth Electronics Limited | Administrative & support | 2004 |
| Cosworth Group Holdings Limited | Financial services | 2007 |
| Cosworth Limited | Professional & scientific | 2004 |
| Cosycolors Ltd | Construction | 2025 |
| Cotorobai Trans Ltd | Transport & logistics | 2016 |
| Cotsmill Marketing Limited | Real estate | 2014 |
| Cotswold & Chiltern Master Thatchers Limited | Extraterritorial | 2005 |
| Cottam's Dental Practice Limited | Health & social care | 2012 |
| Cotter & Co (Northampton) Limited | Real estate | 1988 |
| Cottesbrooke Village Hall Limited | Real estate | 2011 |
| Cotton END Brewery Company Limited | Manufacturing | 2014 |
| Cotton END Car Service Ltd | Wholesale & retail | 2026 |
| Cotton Property & Investments Limited | Real estate | 2019 |
| Cottons Group Services Ltd | Financial services | 2022 |
| Cottons Wealth Limited | Professional & scientific | 2026 |
| Cottontails Childcare Ltd | Education | 2015 |
| Cotu Brewing Ltd | Manufacturing | 2025 |
| Coulson Design & Build Ltd | Professional & scientific | 2021 |
| Coulson Property Improvements Ltd | Construction | 2024 |
| Counsel on Demand Ltd | Professional & scientific | 2020 |
| Counter Fitters Ltd. | Construction | 2014 |
| Countess Court Management Company Limited | Households | 1987 |
| Country Lion (Northampton) Limited | Transport & logistics | 1952 |
| Country Oak Service Ltd | Construction | 2019 |
| Country Properties Bedford Ltd | Real estate | 2014 |
| Countrymile Tech Solutions Ltd | Information & communication | 2021 |
| Countryside Potential Ltd | Professional & scientific | 2022 |