| Caspian Pizza Coventry Road Ltd | Hospitality | 2024 |
| Caspian Pizza Yardley Wood Ltd | Hospitality | 2025 |
| Caspian Take Away (Dudley) Ltd | Hospitality | 2017 |
| Caspian(Cumberia) Foods Limited | Hospitality | 2022 |
| Cass Service Ltd | Other services | 2017 |
| Cassafky Limited | Health & social care | 2022 |
| Cassell Canine Ltd | Wholesale & retail | 2025 |
| Cassian Compliance Ltd | Professional & scientific | 2012 |
| Cassidy Developments Ltd | Real estate | 2025 |
| Cast Hollow-Ware Limited | Professional & scientific | 1920 |
| Castillo Spanish Holdings LP | | 2018 |
| Castle and Co Housing Ltd | Other services | 2022 |
| Castle Assets and Investments Limited | Real estate | 2016 |
| Castle Avon Limited | Information & communication | 2024 |
| Castle Bromwich Cars Ltd | Wholesale & retail | 2013 |
| Castle Bromwich Hall Hotel Limited | Hospitality | 2013 |
| Castle Bromwich Historic Gardens Events Ltd | Hospitality | 2025 |
| Castle Bromwich Historic Gardens Retail Ltd | Wholesale & retail | 2025 |
| Castle Bromwich Tree & Fencing Service Ltd | Administrative & support | 2016 |
| Castle Carpentry Coleshill Limited | Construction | 2001 |
| Castle Cars Birmingham Ltd | Wholesale & retail | 2009 |
| Castle Cars Ltd | Transport & logistics | 2017 |
| Castle Cartons (2011) Limited | Financial services | 2011 |
| Castle Cartons (Holdings) Limited | Manufacturing | 2008 |
| Castle Commercial Limited | Financial services | 2018 |
| Castle Diner Limited | Hospitality | 2018 |
| Castle Doors Ltd | Manufacturing | 1996 |
| Castle Equity Limited | Professional & scientific | 2007 |
| Castle F&B Ltd | Hospitality | 2019 |
| Castle Galleries Retail Limited | Extraterritorial | 2009 |
| Castle Glow Ltd | Other services | 2025 |
| Castle Green Residents Management Company Limited | Households | 2025 |
| Castle Grove Consultancy Limited | Health & social care | 2022 |
| Castle Grove Nottingham Limited | Real estate | 2024 |
| Castle Hills Associates Limited | Real estate | 2014 |
| Castle Inn Ryde Ltd | Administrative & support | 2018 |
| Castle Marble Limited | Manufacturing | 2018 |
| Castle Mezzanine Limited | Professional & scientific | 2007 |
| Castle Pets Limited | Wholesale & retail | 2026 |
| Castle Priory Press LLP | | 2024 |
| Castle Property Solutions Ltd | Real estate | 2025 |
| Castle Square Carpets Limited | Wholesale & retail | 2025 |
| Castle Vale Community Fund | Administrative & support | 1997 |
| Castle Vale Fish Bar Ltd | Wholesale & retail | 2026 |
| Castle Vale Property Company Limited | Real estate | 2023 |
| Castle Vale Service Station Ltd | Wholesale & retail | 2021 |
| Castle View (Studley) Ltd | Construction | 2025 |
| Castle Warehouse Management Limited | Wholesale & retail | 2011 |
| Castlecroft Chippy Ltd | Other services | 2015 |
| Castlegate Co Living Ltd | Real estate | 2026 |
| Castlehall Building Services Ltd | Construction | 2010 |
| Castlehigh Limited | Hospitality | 2013 |
| Castlerock Medicals Limited | Health & social care | 2022 |
| Castlerooms Ltd | Hospitality | 2020 |
| Castleward Management Company Limited | Households | 2013 |
| Castleward Phase 3 Block 1 and 2 Residents Management Company Limited | Households | 2023 |
| Castors and Wheels Direct Limited | Manufacturing | 1998 |
| Casucocsc Ltd | Administrative & support | 2026 |
| Cat 20 Ltd | Extraterritorial | 2017 |
| Cat Motors Limited | Wholesale & retail | 2025 |
| Cat's EYE Production Ltd | Information & communication | 2022 |
| Cataclysm Film Ltd | Information & communication | 2026 |
| Cataforce Limited | Hospitality | 1971 |
| Catalin Amna Ltd | Administrative & support | 2016 |
| Catalin Andrei Ltd | Manufacturing | 2018 |
| Catalin Bricklayer and Roofing Ltd | Construction | 2020 |
| Catalin Niculescu Ltd | Other services | 2018 |
| Catalina Construct Design Ltd | Construction | 2020 |
| Catalyst & Diamond Property Ltd | Real estate | 2023 |
| Catalyst 4 Change Community Interest Company | Professional & scientific | 2017 |
| Catalyst Branding Group Ltd | Financial services | 2025 |
| Catalyst Commercial Services Limited | Professional & scientific | 2001 |
| Catalyst Contracting Ltd | Construction | 2013 |
| Catalyst Dataworks Ltd | Information & communication | 2026 |
| Catalyst Design Ltd | Professional & scientific | 2018 |
| Catalyst Mutual Enterprise C.I.C. | Hospitality | 2012 |
| Catapult Accounting Ltd | Professional & scientific | 2024 |
| Catchpole Pension Nominees Limited | Real estate | 1997 |
| Catchy Deals Limited | Wholesale & retail | 2026 |
| Catchy Nails Ltd | Other services | 2023 |
| Cateaton Limited | Construction | 2003 |
| Catenated Carbon Consultancy Ltd | Professional & scientific | 2019 |
| Cater Care U.K. Limited | Manufacturing | 2009 |
| Catering by DRE Ltd | Professional & scientific | 2025 |
| Catering Direct Supplies Ltd | Wholesale & retail | 2025 |
| Catering Equipment Birmingham Ltd | Wholesale & retail | 2017 |
| Catering Equipment Solutions by RL Ltd | Wholesale & retail | 2025 |
| Catering Kitchens Solutions Ltd | Wholesale & retail | 2024 |
| Catering Logistic Ltd | Hospitality | 2018 |
| Catering Sutton Ltd | Hospitality | 2022 |
| Cateringbase Ltd | Wholesale & retail | 2011 |
| Catermarke Limited | Wholesale & retail | 2019 |
| Caterpillar CYF Limited | Administrative & support | 2012 |
| Caterpillar Housing Ltd | Real estate | 2021 |
| Caterpillar Property Investments Ltd | Real estate | 2023 |
| Caters Photographic Ltd | Professional & scientific | 2014 |
| Caters Properties Ltd | Real estate | 2020 |
| Caterways Limited | Extraterritorial | 2002 |
| Catharsis Films Ltd | Information & communication | 2021 |
| Cathay - Euro (UK) Limited | Real estate | 2002 |