| C & D Cycles Limited | Wholesale & retail | 2000 |
| C a Atkinson Architectural Services Ltd | Professional & scientific | 2024 |
| C a Contracting Ltd | Construction | 2026 |
| C B Venn Driving Services Ltd | Transport & logistics | 2020 |
| C Davis Properties Limited | Real estate | 2001 |
| C Day Developments Ltd | Wholesale & retail | 2017 |
| C Dicks and Sons Limited | Agriculture & fishing | 1999 |
| C J H and M N Developments Ltd | Construction | 2023 |
| C J H Groundworks Ltd | Administrative & support | 2023 |
| C P R Builders Limited | Construction | 1999 |
| C&C Groundwork and Landscaping Limited | Construction | 2019 |
| C&G Brickwork Limited | Construction | 2016 |
| C&G Cleaning Solutions Limited | Administrative & support | 2025 |
| C&I Logistics Ltd | Transport & logistics | 2015 |
| C&L Pproperty Ltd | Real estate | 2026 |
| C&M Baker Ltd | Hospitality | 2018 |
| C-Bia Services & Solutions Ltd | Information & communication | 2017 |
| C-Quester Pro Limited | Professional & scientific | 2022 |
| C. & S. Parker Limited | Information & communication | 1976 |
| C. C. Realisations Limited | Extraterritorial | 1919 |
| C.F.S Brixworth Limited | Manufacturing | 2016 |
| C.H. Tomkins Limited | Agriculture & fishing | 1992 |
| C.Me Smart Designs Limited | Manufacturing | 2017 |
| C.N. Spencer Limited | Agriculture & fishing | 1920 |
| C.P.R. (Accounting Services) Limited | Professional & scientific | 2014 |
| C.T.A Plant Ltd | Construction | 2017 |
| C2C Nton Holdings Ltd | Financial services | 2025 |
| CA Fire Solutions Ltd | Public administration | 2025 |
| Cabicorreia Limited | Health & social care | 2022 |
| Cadney Consulting Ltd | Professional & scientific | 2018 |
| Caelus Delisle Solutions Limited | Other services | 2018 |
| Cafe Europaa Ltd | Hospitality | 2026 |
| Caistle Ltd | Information & communication | 2023 |
| Cake Inn Kettering Limited | Real estate | 2021 |
| Cale&Co Ltd | Professional & scientific | 2019 |
| Caletoni Ltd | Wholesale & retail | 2019 |
| California Car & Commercials Ltd | Wholesale & retail | 2014 |
| Callahan Creations Ltd | Manufacturing | 2023 |
| CAM Business Services Limited | Administrative & support | 2008 |
| CAM Group Services Ltd | Construction | 2020 |
| Camens Healthcare Ltd | Education | 2015 |
| Campbell Finance Solutions Limited | Professional & scientific | 2020 |
| CAMPEONES1516 Limited | Financial services | 2023 |
| Canvas ME Ltd | Construction | 2020 |
| Cape Lekker Limited | Hospitality | 2008 |
| Capstone Professional Cleaning Contracts Limited | Other services | 2008 |
| Carbon Clarity Ltd | Professional & scientific | 2010 |
| Carbon Green Smarter Engines Ltd | Professional & scientific | 2017 |
| Cardinal Demolition Limited | Construction | 2011 |
| Cardinal Masonry Limited | Construction | 2003 |
| Carduan Ltd | Information & communication | 2024 |
| Care United Ltd | Health & social care | 2023 |
| Care With Compassion Limited | Health & social care | 2014 |
| Carina Electronics Limited | Professional & scientific | 2008 |
| Carisbrooke Construction Limited | Construction | 2024 |
| Carl Waters Project Controls Ltd | Professional & scientific | 2023 |
| Carlisle Tutoring Company Ltd | Education | 2023 |
| Carlton Estates (Narborough) Limited | Real estate | 2004 |
| Carlton Heating Solutions Limited | Construction | 2022 |
| Carlyle Watts Limited | Professional & scientific | 1990 |
| Caroline Wilson Limited | Professional & scientific | 2015 |
| Carpets and Furniture 4U Limited | Wholesale & retail | 2003 |
| Carpetwise (Kettering) Limited | Wholesale & retail | 1999 |
| Carr's Welding Technologies Limited | Manufacturing | 2000 |
| Carrington Cars (Northants) Limited | Wholesale & retail | 2009 |
| Carrington Industries Limited | Financial services | 1900 |
| Carter Care Solutions Ltd | Professional & scientific | 2025 |
| Carter Williams Limited | Real estate | 2014 |
| Cartvibe Ltd | Wholesale & retail | 2024 |
| Casa Amor Ltd | Wholesale & retail | 2023 |
| Cascade AI Limited | Information & communication | 2025 |
| Casewell Glazing Ltd | Construction | 2026 |
| Casey & Reeve Limited | Real estate | 2006 |
| Cashflow Experts Limited | Professional & scientific | 2017 |
| Cast Iron Rainwater Limited | Wholesale & retail | 2012 |
| Cast Iron Superstore Ltd | Wholesale & retail | 2017 |
| Cast Solutions Limited | Construction | 2018 |
| Castelnau Investments Limited | Real estate | 1997 |
| Castle Rising Holdings Limited | Administrative & support | 1978 |
| Castle Ventures Limited | Manufacturing | 2006 |
| Castleton Advisory Ltd | Professional & scientific | 2025 |
| Catalyst Property Search Ltd | Real estate | 2009 |
| Catlin Building Services Limited | Construction | 2002 |
| Catlin Environmental Services Ltd | Construction | 2013 |
| Caveat Viator Ltd | Administrative & support | 2012 |
| Cavendish Electricals & Services Limited | Construction | 2022 |
| Cawston Press Limited | Manufacturing | 2000 |
| CB Company Management Limited | Administrative & support | 2011 |
| CB Contracting Services Limited | Professional & scientific | 2025 |
| CB Engineering & Projects Ltd | Professional & scientific | 2025 |
| CB Support Care Ltd | Extraterritorial | 2023 |
| CBM Haulage Ltd | Transport & logistics | 2024 |
| CD Telecoms Limited | Information & communication | 2018 |
| CDR Build Ltd | Manufacturing | 2025 |
| CDS Aviation Limited | Transport & logistics | 2008 |
| CDS Premium Solutions Limited | Administrative & support | 2024 |
| Cdsp Ltd | Real estate | 2021 |
| Ceb-Drive Ltd | Transport & logistics | 2016 |
| Cebula-Hanz Ltd | Information & communication | 2022 |
| Celestial Holdings Ltd | Financial services | 2023 |