| Castle Civils & Construction Ltd. | Construction | 2019 |
| Castle Dwellings Leeds Ltd | Real estate | 2015 |
| Castle Grange (Pontefract) Management Company Limited | Households | 2005 |
| Castle Hill (Bardsey) Management Limited | Households | 2004 |
| Castle Homes (UK) Limited | Construction | 2003 |
| Castle Keep Building Services Ltd | Construction | 2020 |
| Castle Paving & Sons Limited | Construction | 2016 |
| Castle Powder Coating Ltd | Manufacturing | 2014 |
| Castle Properties (MCR) Ltd | Real estate | 2002 |
| Castle Refurbishments Ltd | Construction | 2017 |
| Castle Support Services PLC | Professional & scientific | 2005 |
| Castle Trinity Limited | Extraterritorial | 2017 |
| Castle Window Cleaning Ltd | Construction | 2025 |
| Castleam Limited | Real estate | 1980 |
| Castlecroft Limited | Real estate | 1992 |
| Castlefield Group Limited | Administrative & support | 2021 |
| Castlefield Recruitment Limited | Administrative & support | 2010 |
| Castleford Carpet Depot Limited | Wholesale & retail | 2005 |
| Castleford P & H Ltd. | Administrative & support | 2018 |
| Castleford Properties Limited | Real estate | 1964 |
| Castlehead Gardens Management Co. Limited | Households | 1980 |
| Castlehill Estate Agents Limited | Real estate | 2005 |
| Castlehouse Construction Ltd | Construction | 2009 |
| Castleings Coatings Ltd | Construction | 2023 |
| Castles Shopfitters Limited | Wholesale & retail | 1971 |
| Castletex (Clothes) Limited | Professional & scientific | 1962 |
| Castleton Mill MOT Station Ltd | Professional & scientific | 2019 |
| Castlevale Limited | Construction | 2009 |
| Castleway Investments Limited | Professional & scientific | 2007 |
| Castores Consultancy Ltd | Professional & scientific | 2023 |
| Casual Minds Terrace Wear Limited | Wholesale & retail | 2023 |
| Casus Group Limited | Financial services | 2019 |
| Cat & Cake Ltd | Wholesale & retail | 2024 |
| Cat Among the Pigeons Ltd | Professional & scientific | 2019 |
| Cat and Dave Ltd | Information & communication | 2020 |
| Cat Limited | Other services | 1995 |
| Cat Property Solutions Ltd | Real estate | 2017 |
| Catabolic Chemicals Ltd | Manufacturing | 2021 |
| Catalan Soccer LLP | | 2016 |
| Catalina Developments Limited | Construction | 2026 |
| Catalogue Graphic Design Limited | Professional & scientific | 2014 |
| Catalyst Development Management Limited | Professional & scientific | 2019 |
| Catalyst Incorporated Limited | Wholesale & retail | 2025 |
| Catalystnex Global Partners Limited | Wholesale & retail | 2025 |
| Catalystnex Limited | Information & communication | 2023 |
| Catamaran Technology Ltd | Information & communication | 2022 |
| Catapult Sports Limited | Administrative & support | 2013 |
| Catastea Delivery Ltd | Transport & logistics | 2019 |
| Catchweight Ltd | Arts & recreation | 2025 |
| Catcom Services Ltd | Construction | 2017 |
| Cater Care Leeds Ltd | Other services | 2008 |
| Catering (Leeds) Ltd | Hospitality | 2024 |
| Catering Solutions CB Ltd | Hospitality | 2024 |
| Cathedral Builders (Bradford) Limited | Construction | 2004 |
| Catherine Daniels Consultancy Ltd | Other services | 2015 |
| Catherine Kershaw GUY Limited | Health & social care | 2023 |
| Catherine W Eyewear Limited | Wholesale & retail | 2026 |
| CATHERINESPV1 Ltd | Real estate | 2025 |
| Cathexis Investment Management (UK) Limited | Real estate | 2022 |
| Cathexis UK Holding II Limited | Administrative & support | 2017 |
| Cathexis UK Holdings III Limited | Financial services | 2019 |
| Cathexis UK Holdings IV Limited | Financial services | 2022 |
| Cathexis UK Holdings Limited | Financial services | 2015 |
| Catholic Care (Diocese of Leeds) | Health & social care | 1982 |
| Catnaps Farm Limited | Agriculture & fishing | 2013 |
| Catrake Limited | Construction | 1991 |
| Catrock IT Ltd | Information & communication | 2019 |
| Causatum Ltd | Other services | 2014 |
| Causeway House Property Limited | Real estate | 2023 |
| Causeway Medical Ltd | Health & social care | 2019 |
| Caval Limited | Administrative & support | 2008 |
| Cavalier Properties Limited | Real estate | 2025 |
| Cavanis Italian Ltd | Hospitality | 2017 |
| Cavaro Ltd | Real estate | 2025 |
| Cave Coffee Ltd | Hospitality | 2022 |
| Cavendish Court Management Company (Drighlington) Limited | Households | 2004 |
| Cavendish Digital Ltd | Professional & scientific | 2023 |
| Cavendish Kane & Associates Limited | Other services | 2014 |
| Cavendish Mews(Maintenance) Limited | Households | 1972 |
| Caveo Ltd | Construction | 2022 |
| Caverna Ltd | Households | 2021 |
| Cavero Quantum Limited | Information & communication | 2020 |
| Cavill Properties Ltd | Real estate | 2026 |
| Cavina Solutions Limited | Administrative & support | 2017 |
| Caxton Consulting Services Ltd | Professional & scientific | 2012 |
| Caxton Holdings Ltd | Real estate | 2019 |
| Caygill Mortgage Solutions Ltd | Financial services | 2026 |
| Cayton Fitzpatrick Construction Ltd | Construction | 2025 |
| Caza Furniture Limited | Wholesale & retail | 2024 |
| Cazeus Holdings Ltd | Financial services | 2025 |
| Cazz Properties Ltd | Real estate | 2025 |
| CB Capital Partners Ltd | Professional & scientific | 2026 |
| CB Change Accountancy Limited | Professional & scientific | 2023 |
| CB Financial Planning Limited | Professional & scientific | 2024 |
| CB Leisure Holdings Limited | Real estate | 2026 |
| CB Projects & Planning Ltd | Professional & scientific | 2024 |
| CB Projects Ltd | Professional & scientific | 2025 |
| CB Properties Ltd | Real estate | 2022 |
| CB Realisations Limited | Wholesale & retail | 1995 |
| CB Software Consultancy Limited | Information & communication | 2025 |