| Carlton House (Chelmsford) Limited | Construction | 2018 |
| Carlton House (Chelmsford) SUB Limited | Real estate | 2020 |
| Carlton House Assets Limited | Hospitality | 2025 |
| Carlton Place Management Limited | Households | 1989 |
| Carlton Training Limited | Education | 2002 |
| Carman Contracting Ltd | Administrative & support | 2020 |
| Carman Properties Limited | Administrative & support | 2023 |
| Carmax International Property Ltd | Real estate | 2023 |
| Carmelite (Golders Green) Management Limited | Households | 2012 |
| Carmen Tapas Ltd | Hospitality | 1996 |
| Carmichael Property Hub Ltd | Real estate | 2019 |
| Carney Mechanical Ltd | Construction | 2026 |
| Carol Ltd | Construction | 2023 |
| Carola Marine Limited | Transport & logistics | 2020 |
| Carole Spiers Group Ltd | Professional & scientific | 2001 |
| Carole Topin Ltd | Professional & scientific | 2013 |
| Caroline Creasy Consulting Ltd | Professional & scientific | 2019 |
| Carpal Plus Ltd | Wholesale & retail | 2026 |
| Carpat Capital Partners Ltd | Construction | 2017 |
| Carpe Diem Promotions Ltd | Arts & recreation | 2019 |
| Carpenters 24/7 Construction Limited | Construction | 2019 |
| Carpet Mart Holdings Limited | Professional & scientific | 1986 |
| Carpet Mart Limited | Wholesale & retail | 1983 |
| Carpol Consulting Ltd | Professional & scientific | 2010 |
| Carramea | Administrative & support | 2011 |
| Carrington Estate Agents Limited | Real estate | 2015 |
| Carrington UK (Holdings) Limited | Financial services | 2006 |
| Carringtons Formal Wear Limited | Wholesale & retail | 2002 |
| Carry PAL Limited | Transport & logistics | 2025 |
| Cars Property Limited | Real estate | 2025 |
| Carsons Real Estate Ltd | Real estate | 2022 |
| Carta Dinero Limited | Real estate | 2024 |
| Cartdrops Ltd | Wholesale & retail | 2024 |
| Carter & Co Construction Limited | Construction | 2020 |
| Carter & Co Homes Limited | Construction | 2025 |
| Carter Troy Limited | Professional & scientific | 2012 |
| Cartgator Limited | Wholesale & retail | 2020 |
| Carthy Caravans Ltd | Hospitality | 2024 |
| Cartopia Ltd | Wholesale & retail | 2010 |
| Cartx Ltd | Wholesale & retail | 2020 |
| Carvers Property Services Limited | Real estate | 2022 |
| Carveth Productions Limited | Other services | 1982 |
| Carwash A1 Limited | Administrative & support | 2026 |
| Carzaar Ltd | Wholesale & retail | 2025 |
| CAS Holdings Limited | Financial services | 2015 |
| CAS Home London Limited | Real estate | 2024 |
| CAS Property Limited | Construction | 2014 |
| Casa & Hogar Limited | Real estate | 2020 |
| Casa Barber Ltd | Real estate | 2025 |
| Casa DA Padel Ltd | Wholesale & retail | 2025 |
| Casa Damo Ltd | Professional & scientific | 2022 |
| Casa Natu Ltd | Hospitality | 2024 |
| Casa Nube Property Group Ltd | Real estate | 2025 |
| Casa Properties North Limited | Real estate | 2017 |
| Casaba Management Limited | Real estate | 2024 |
| Casandra Construct Ltd | Construction | 2016 |
| Cascade RE Holdings Ltd | Real estate | 2023 |
| Case Closed Phone Accessories Ltd | Wholesale & retail | 2024 |
| Case Studies Associates Limited | Professional & scientific | 2025 |
| Casey's Tavern Limited | Hospitality | 2025 |
| Cash Lighting Ltd | Information & communication | 2021 |
| Cashayjah Ltd | Wholesale & retail | 2018 |
| Cashbackpoint Ltd | Professional & scientific | 2014 |
| Cashcounts Ltd | Wholesale & retail | 2024 |
| Cashflow Consultancy (UK) Limited | Professional & scientific | 2009 |
| Cashorina Limited | Hospitality | 2010 |
| Casino Tours Abroad Limited | Administrative & support | 2011 |
| Casipillai Designer Collection Limited | Wholesale & retail | 2010 |
| Cass Associates London Ltd | Health & social care | 2014 |
| Cass Property Investments Ltd | Real estate | 2019 |
| Castelo Construction Ltd | Construction | 2023 |
| Castiell Limited | Water & waste | 2018 |
| Castiello Holdings Ltd | Information & communication | 2026 |
| Castle 2011 Limited | Construction | 2011 |
| Castle Black Consultancy Ltd | Professional & scientific | 2019 |
| Castle Black Properties Ltd | Real estate | 2017 |
| Castle Property London Ltd | Construction | 2017 |
| Castlegate 721 Limited | Real estate | 2014 |
| Castlepines Limited | Construction | 2018 |
| Castlereagh House (2022) Ltd | Households | 2022 |
| Castlereagh House RTM Company Limited | Real estate | 2007 |
| Cat and COW Media Limited | Information & communication | 2024 |
| Cataallex Ltd | Energy | 2026 |
| Catalonia Brooks Ltd | Real estate | 2025 |
| Catalysed Productions Limited | Professional & scientific | 2022 |
| Catalyst DMS UK Ltd | Financial services | 2024 |
| Catalyst IT Consultancy Ltd | Information & communication | 2021 |
| Catalyst Tuition Ltd | Education | 2018 |
| Catapult Works Limited | Arts & recreation | 2017 |
| Catch Cabin Limited | Wholesale & retail | 2017 |
| Catchi Ltd | Wholesale & retail | 2024 |
| Catching Dust Limited | Information & communication | 2019 |
| Catco Kids LLP | | 2006 |
| Catdromeda Accounting Limited | Professional & scientific | 2016 |
| Catdromeda Darts Ltd | Professional & scientific | 2020 |
| Catdromeda Holdings Ltd | Financial services | 2020 |
| Catena Group Ltd | Hospitality | 2022 |
| Catering Tech Ltd | Manufacturing | 2025 |
| Catford Assets Ltd | Real estate | 2010 |
| Catherine Healthcare Limited | Health & social care | 2013 |