| County Repair Center Ltd | Wholesale & retail | 2014 |
| Couponshop Limited | Wholesale & retail | 2013 |
| Course Genie Limited | Education | 2025 |
| Court & Co Property Solutions Limited | Real estate | 2007 |
| Courtenay Property Ltd | Real estate | 2021 |
| Courtney Trading International Metals Ltd | Water & waste | 2025 |
| Couture Cars Ltd | Other services | 2014 |
| Cove Street Publications Limited | Administrative & support | 2022 |
| Covelle Group Ltd | Information & communication | 2026 |
| Coventry Health Limited | Real estate | 2005 |
| Cowans Direct Limited | Wholesale & retail | 2007 |
| Cowgirls Closet Ltd | Wholesale & retail | 2024 |
| CP Shutters Ltd | Wholesale & retail | 2014 |
| CPG (Homes Counties) Limited | Construction | 2019 |
| CPG (Kent) Limited | Financial services | 2019 |
| CPG (South Coast) Limited | Financial services | 2019 |
| CPG (South East) Limited | Financial services | 2019 |
| CPM (Vehicle Collections) Ltd | Transport & logistics | 2025 |
| CPS Paving & Landscapes Ltd | Administrative & support | 2022 |
| Crafts Collective Ltd | Wholesale & retail | 2025 |
| Cranleigh Court Management (Cubbington) Limited | Households | 1978 |
| Crawfords Construction Limited | Construction | 2007 |
| Crazy Baker Properties Ltd | Real estate | 2024 |
| Create and Renovate Ltd | Construction | 2024 |
| Create Business Hub Ltd | Administrative & support | 2018 |
| Createcg Ltd | Professional & scientific | 2019 |
| Creative Art Ltd | Administrative & support | 2003 |
| Creative Kingdom Books Limited | Wholesale & retail | 2011 |
| Creative Sport & Leisure Ltd | Education | 2007 |
| Credence Exchange Limited | Professional & scientific | 2023 |
| CREE8 Limited | Construction | 2019 |
| Crescent Electrical Services Ltd | Construction | 2014 |
| Cresco Group Limited | Professional & scientific | 2016 |
| Crestmount Electrical & Mechanical Ltd | Construction | 2013 |
| Crextive Ltd | Information & communication | 2023 |
| Cricket Cubs Ltd | Arts & recreation | 2026 |
| Cricket Mentoring and Coaching Limited | Arts & recreation | 2016 |
| Crimswift Managing Agents Limited | Real estate | 1999 |
| Cris & JON Ltd | Construction | 2018 |
| Crisp Design Services Limited | Professional & scientific | 2005 |
| Criss Cross Agency Limited | Professional & scientific | 2022 |
| Critical Services Ltd | Professional & scientific | 2024 |
| Croker & Mitchell Limited | Real estate | 1973 |
| Cromarty House Limited | Households | 1992 |
| Cross & Young Ltd | Professional & scientific | 2025 |
| Cross Court Residence Limited | Real estate | 2021 |
| Cross Further Ltd | Manufacturing | 2015 |
| Cross Real Estate Agents Ltd | Real estate | 2019 |
| Crossley Financial Solutions Limited | Financial services | 2008 |
| Crossley Property Investments Limited | Real estate | 2016 |
| Croucher Needham (Essex) LLP | | 2009 |
| Croucher Needham Ltd | Professional & scientific | 2006 |
| Crouchview Supplies Ltd | Wholesale & retail | 2022 |
| Crow Green Management Limited | Real estate | 2012 |
| Crow Hill Limited | Wholesale & retail | 2022 |
| Crowdspeak Ltd | Professional & scientific | 2010 |
| Crown Crust Limited | Hospitality | 2025 |
| Crown Crypto Consultancy Ltd | Education | 2021 |
| Crown Residential Ltd | Other services | 2011 |
| Crownford Energy and Building Compliance Limited | Professional & scientific | 2025 |
| Crownwalk Takeaway Limited | Hospitality | 2011 |
| Crunch Payments Holdings Limited | Information & communication | 2020 |
| Crunch Payments Limited | Administrative & support | 2019 |
| Crux Financial Solutions Limited | Financial services | 2026 |
| Crystal Collections Limited | Professional & scientific | 1997 |
| Crystal Serenity Counselling & Psychotherapy Services Ltd | Health & social care | 2015 |
| Crystale Estates Limited | Real estate | 2021 |
| CS Holdings Group Ltd | Financial services | 2025 |
| CSB Cooling Ltd | Construction | 2025 |
| CSI Network Services Ltd | Construction | 2022 |
| CSJ Options Ltd | Financial services | 2017 |
| CSL (Central Services) Limited | Information & communication | 2018 |
| CSM Installations Limited | Construction | 2008 |
| CSM London Holdings Ltd | Construction | 2017 |
| CST Essex Ltd | Other services | 2019 |
| CT Roofing Ltd | Construction | 2014 |
| Ctbond Limited | Professional & scientific | 2024 |
| CTC Building Services Ltd | Other services | 2012 |
| CTE Holdings Group Ltd | Financial services | 2026 |
| Ctey Consultants Limited | Professional & scientific | 2026 |
| CU5K Ltd | Wholesale & retail | 2024 |
| Cube Hvac-R Services Limited | Construction | 2010 |
| Cube IT Support Limited | Information & communication | 2015 |
| Cube Supplies Limited | Information & communication | 2019 |
| Cudmon Limited | Professional & scientific | 2012 |
| CUE Virtue Ltd | Administrative & support | 2016 |
| Cullen Builders Group Ltd | Construction | 2025 |
| Cult Beverages Limited | Wholesale & retail | 2025 |
| Cura Art Limited | Arts & recreation | 2019 |
| Curtains 4 YOU Limited | Wholesale & retail | 1999 |
| Curtis Motor Sport Ltd | Administrative & support | 2024 |
| Curves & Couture Ltd | Wholesale & retail | 2013 |
| Custom Cabins Essex Ltd | Manufacturing | 2019 |
| Custom Contracts Limited | | 1988 |
| Custom Crafted Limited | Construction | 2015 |
| Custom Number Plates Onthego Ltd | Manufacturing | 2025 |
| Custom Orthoses Alterations Ltd | Health & social care | 2019 |
| Custom Pet Enclosures Limited | Construction | 2026 |
| Custom Print Online Limited | Manufacturing | 2023 |
| Customade London Limited | Manufacturing | 2025 |