| Castle Acres Development Limited | Professional & scientific | 1936 |
| Castle Assessments Ltd | Health & social care | 2023 |
| Castle Chase Ltd | Hospitality | 2022 |
| Castle Collision Care Limited | Wholesale & retail | 2024 |
| Castle Embroidering Limited | Other services | 2001 |
| Castle Family Legal Services Limited | Professional & scientific | 2020 |
| Castle Park Hotel Trading Ltd | Hospitality | 2014 |
| Castle Park Services Limited | Professional & scientific | 2001 |
| Castle Street Dental Limited | Health & social care | 2012 |
| Castle Window Installations Limited | Construction | 2019 |
| Castlecare Education Limited | Education | 2002 |
| Castlecare Group Limited | Professional & scientific | 2004 |
| Castlecare Holdings Limited | Professional & scientific | 1987 |
| Castledene Builders Ltd | Construction | 2023 |
| Castledene Estates Ltd | Real estate | 2023 |
| Castlefields Prestige Ltd | Transport & logistics | 2014 |
| Castleview (Leicester) Ltd | Construction | 2023 |
| Castleville Property Ltd | Real estate | 2004 |
| Castlewood Carpentry and Joinery Ltd | Construction | 2021 |
| Cat Girl Investment Ltd | Real estate | 2012 |
| Cat Property Investments Ltd | Real estate | 2016 |
| Catalyst Academy Tuition Ltd | Education | 2025 |
| Catalyst Clothing Ltd | Wholesale & retail | 2025 |
| Catalyst IT Ltd | Information & communication | 2025 |
| Catalyst SAS Limited | Information & communication | 2025 |
| Catapult Venture Managers Limited Partnership | | 2002 |
| Catdrive Ltd | Wholesale & retail | 2022 |
| Cate-R-Us Limited | Hospitality | 2005 |
| Cater Source Ltd | Manufacturing | 2025 |
| Catering Service S.R. Ltd | Hospitality | 2021 |
| Catering Trader Limited | Information & communication | 2011 |
| Caterme Ltd | Hospitality | 2024 |
| Caterpillar (U.K.) Limited | Manufacturing | 1950 |
| Caterpillar Commercial Northern Europe Limited | Administrative & support | 1999 |
| Caterpillar UK Employee Trust Limited | Extraterritorial | 2000 |
| Caterpillar UK Holdings Limited | Administrative & support | 1992 |
| Catherine Place Property 4 Limited | Real estate | 2022 |
| Catherston Skills Ltd | Transport & logistics | 2014 |
| Cathode Services Ltd | Professional & scientific | 2024 |
| Cathsar Limited | Financial services | 2012 |
| Cathy Potts HR Solutions Limited | Administrative & support | 2015 |
| Catilyst Academy UK CIC | Education | 2025 |
| Catley Engineering Ltd | Wholesale & retail | 2012 |
| Catley Properties Limited | Real estate | 2021 |
| Cats ARE NOT Peas Ltd | Arts & recreation | 2017 |
| Cats Hill Plant Limited | Administrative & support | 2002 |
| Cats in Need Cyprus Community Interest Company | Wholesale & retail | 2019 |
| Catstudios Ltd | Arts & recreation | 2024 |
| Catterleaf Ltd | Wholesale & retail | 2024 |
| Cattgut Surgery Ltd | Health & social care | 2015 |
| Cattigara Limited | Wholesale & retail | 2026 |
| Cattle and Smoke Ltd | Hospitality | 2023 |
| Catwalk Limited | Real estate | 1993 |
| Caunton Haulage Ltd | Transport & logistics | 2014 |
| Cavaday Coaching Limited | Arts & recreation | 2023 |
| Cavallo Ltd | Administrative & support | 2016 |
| Cavavan Ltd | Hospitality | 2022 |
| Cave Diving Group Northern Section Limited | Arts & recreation | 2024 |
| Cave Valley Caribbean Takeaway Ltd | Hospitality | 2025 |
| Caveco Limited | Professional & scientific | 2007 |
| Cavell Oldham Ltd | Professional & scientific | 2024 |
| Cavelles Limited | Information & communication | 1999 |
| Cavendish & London Property Group Limited | Real estate | 2016 |
| Cavendish Filters Ltd | Administrative & support | 2008 |
| Cavendish Keighley Properties Limited | Real estate | 2012 |
| Cavendish Kitchens Limited | Construction | 2004 |
| Cavendish Property Comp Ltd | Real estate | 2025 |
| Cavendish Road (Leicester) Management Company Limited | Professional & scientific | 2005 |
| Cavenham Ability Ltd | Transport & logistics | 2015 |
| Cavga Ltd | Real estate | 2022 |
| Cavity Creative Ltd | Information & communication | 2024 |
| Cavlon Developments Ltd | Construction | 2025 |
| Cavlon Quarter Ltd | Real estate | 2025 |
| Cavra Group Ltd | Energy | 2025 |
| Cawdor Capital Partners Limited | Real estate | 2022 |
| Cawsand Maximum Ltd | Transport & logistics | 2014 |
| Cawtonville Action Ltd | Wholesale & retail | 2014 |
| Caxton Heights Ltd | Real estate | 2022 |
| Cayk Beauty Limited | Manufacturing | 2022 |
| Caylil Ltd | Other services | 2019 |
| Cazley Richards Solutions Ltd | Transport & logistics | 2025 |
| CB & PB Holdings Ltd | Information & communication | 2019 |
| CB Business Analysis Limited | Administrative & support | 2025 |
| CB Flue & Chimney Consultants Ltd | Construction | 2017 |
| CB Geoservices Ltd | Professional & scientific | 2012 |
| CB Hoofcare Limited | Agriculture & fishing | 2016 |
| CB Hospitality Management Ltd | Professional & scientific | 2024 |
| CBA Business Solutions Limited | Administrative & support | 2001 |
| CBA Dental Nurse Training Ltd | Professional & scientific | 2022 |
| CBD Global (U.K) Limited | Manufacturing | 2018 |
| CBD My Remedy UK Ltd | Wholesale & retail | 2019 |
| CBD Spectrum Limited | Manufacturing | 2018 |
| Cbdistribution (Southern) Ltd | Transport & logistics | 2015 |
| Cbdmelc Ltd | Wholesale & retail | 2025 |
| Cbej Holdings Limited | Real estate | 2018 |
| Cbgc Creative Industries Ltd | Administrative & support | 2018 |
| CBO Limited | Construction | 2020 |
| CBR Transport Ltd | Transport & logistics | 2014 |
| CBS Plant Ltd | Administrative & support | 2025 |
| CBS Sales Ltd | Wholesale & retail | 2022 |