| Caldw Properties Ltd | Real estate | 2026 |
| Callum David & Co. Ltd. | Administrative & support | 2021 |
| CAM Security Limited | Manufacturing | 2011 |
| Campbell and Law Building Services Ltd | Energy | 2018 |
| Campbell and Law Group Ltd | Professional & scientific | 2025 |
| Campioni Havering Ltd | Professional & scientific | 2023 |
| Candybel Cuisine Ltd | Hospitality | 2024 |
| Canopact Ltd | Information & communication | 2025 |
| Capgroup INT Ltd | Wholesale & retail | 2021 |
| Capital Compliance Ltd | Professional & scientific | 2021 |
| Capital Electrical Ltd | Construction | 2017 |
| Capitall Holdings Limited | Financial services | 2017 |
| Capitall Ltd | Professional & scientific | 2013 |
| Care Cottage Limited | Administrative & support | 1994 |
| Careload Ltd | Transport & logistics | 2025 |
| CARER2U Limited | Administrative & support | 2026 |
| CAREUK247 Group Ltd | Health & social care | 2024 |
| CAREUK247 Peterborough Ltd | Health & social care | 2024 |
| Carfar Ltd Limited | Other services | 2021 |
| Cargo Matters Limited | Transport & logistics | 2009 |
| Carl Cunard Ltd | Information & communication | 2016 |
| Carlton Road Property Holdings Limited | Real estate | 2019 |
| Carly Rich Property Ltd | Real estate | 2018 |
| Carobin Holdings Ltd | Professional & scientific | 2019 |
| Carooz Ltd | Other services | 2025 |
| Carpe Associates Limited | Information & communication | 1998 |
| Carpenter Consultancy Limited | Information & communication | 2010 |
| Carters Dessert Diner Ltd | Hospitality | 2016 |
| Casey Property Group Limited | Real estate | 2026 |
| Cat Consultants Limited | Professional & scientific | 2019 |
| Catchlight Creative Ltd | Professional & scientific | 2026 |
| Caterpillar 2 Butterfly Childminding Services Ltd | Health & social care | 2023 |
| CBW Retention Through Knowledge Ltd | Professional & scientific | 2011 |
| CD Bissell Projects Ltd | Construction | 2025 |
| Cedar Oak Properties Ltd | Real estate | 2021 |
| Cedar Property Assets Group Ltd | Financial services | 2022 |
| Cemetery Lane Limited | Construction | 2015 |
| Centurion Labz UK Ltd | Wholesale & retail | 2017 |
| Cerrar Drinks Company Limited | Professional & scientific | 2025 |
| CFC Rainham Youth Football Ltd | Arts & recreation | 2024 |
| CFH Catering Ltd | Hospitality | 2024 |
| CGM Brickwork Limited | Construction | 2016 |
| CGM Contracts Limited | Construction | 2019 |
| Chafford Fork Trucks Limited | Administrative & support | 2004 |
| Chagar Clouds Ltd | Wholesale & retail | 2025 |
| Charcoal Paving and Landscapes Ltd | Construction | 2020 |
| Charge Point Electrical Ltd | Construction | 2021 |
| Charming Design Services Limited | Administrative & support | 2024 |
| Chavda Portfolio Limited | Real estate | 2020 |
| Cheam Building Services Ltd | Construction | 2023 |
| Chelba Ltd | Construction | 2024 |
| Chelmsford Histopathologists LLP | | 2018 |
| Chelvaa Homes (PVT) Ltd | Construction | 2020 |
| Cheo Electrical Ltd | Construction | 2026 |
| Cher Hairstyles & Make UP Ltd | Other services | 2025 |
| Cherished Healthcare Ltd | Health & social care | 2025 |
| Cherry Blossom Books Limited | Arts & recreation | 2021 |
| Chessington View Limited | Other services | 1997 |
| Chira and SON Ltd | Health & social care | 2025 |
| Chloe Sandoz Hair Limited | Other services | 2016 |
| Choc Pops Ltd | Hospitality | 2024 |
| Choice Group Ltd | Administrative & support | 2019 |
| Choice Ware Ltd | Hospitality | 2020 |
| Chris Fitzjohn Building Services Ltd | Construction | 2023 |
| Christine Van DER Merwe Limited | Administrative & support | 2012 |
| Churchill Construction Ltd | Construction | 2018 |
| Cidaris Homes Ltd | Real estate | 2025 |
| Cinders Training Ltd | Education | 2023 |
| Cinevation Ltd | Professional & scientific | 2022 |
| Cipura Limited | Transport & logistics | 2016 |
| Circular Design Recruitment Ltd | Professional & scientific | 2024 |
| Cistaxrefunds.Com Ltd | Professional & scientific | 2010 |
| City & Shire Projects Ltd | Construction | 2011 |
| City Limits Holdings Limited | Professional & scientific | 2022 |
| CJG Consultancy Services Limited | Professional & scientific | 2021 |
| CK85 Ltd | Financial services | 2025 |
| Claire Ince Promotions Limited | Arts & recreation | 2013 |
| Claremont Car Sales (UK) Ltd | Wholesale & retail | 2014 |
| Claremont Chemical Company Limited | Wholesale & retail | 1981 |
| Clarity Consulting International Limited | Professional & scientific | 2024 |
| Clavedale Ltd | Construction | 2011 |
| Clean Essex Facilities and Management Ltd | Administrative & support | 2021 |
| Cleanergold Ltd | Administrative & support | 2025 |
| Climaflow Technologies Ltd | Other services | 2025 |
| CLM Unique Services Limited | Administrative & support | 2022 |
| Clockstock Ltd | Administrative & support | 2023 |
| Clockwork Orange MAG Ltd | Administrative & support | 2014 |
| Closedesign Limited | Information & communication | 2004 |
| Closehurst Limited | Extraterritorial | 1982 |
| Cloth N Card Ltd | Wholesale & retail | 2024 |
| Cloud Infrastructure Limited | Information & communication | 2018 |
| Club Manager Limited | Wholesale & retail | 2008 |
| CM Investments Holdings Limited | Administrative & support | 2018 |
| CMA Planning Limited | Administrative & support | 2006 |
| CMC Creative Ltd | Professional & scientific | 2017 |
| CML Equipment Solutions Ltd | Wholesale & retail | 2017 |
| CMS Management Ltd | Professional & scientific | 2024 |
| Coach Denn Limited | Arts & recreation | 2024 |
| Coal House Cuts Ltd | Other services | 2019 |
| Codestack Technologies Limited | Information & communication | 2025 |