| Compassionate Services Ltd | Hospitality | 2025 |
| Compassionate Staff Ltd | Other services | 2012 |
| Competent Staff Ltd | Administrative & support | 2023 |
| Complete Carpentry & Maintenance Ltd | Construction | 2018 |
| Complete Finance Services Limited | Professional & scientific | 2019 |
| Complete Home Care Sussex Ltd | Public administration | 2018 |
| Complete Roofing Southeast Limited | Construction | 2023 |
| Complete Wrap Limited | Other services | 2024 |
| Completely Interiors Southern Limited | Construction | 2011 |
| Compliance Contractors Ltd | Professional & scientific | 2020 |
| Compnd Ltd | Wholesale & retail | 2025 |
| Compusystems UK Limited | Manufacturing | 1995 |
| Computer Design Services Ltd | Information & communication | 2022 |
| Comsrl Ltd | Construction | 2025 |
| Concise CAD Solutions Ltd | Professional & scientific | 2024 |
| Concise Content Marketing Ltd | Information & communication | 2020 |
| Conciseedge Global Concept Ltd | Wholesale & retail | 2026 |
| Concord Investments Ltd | Real estate | 2007 |
| Concorde Housing Ltd | Real estate | 2025 |
| Confident Cyclists Ltd | Education | 2021 |
| Conjoy Investment Partners Limited | Financial services | 2021 |
| Connect UK (Nationwide) Limited | Real estate | 2012 |
| Connect UK Auctions Limited | Other services | 2019 |
| Connect UK Sales Ltd | Other services | 2019 |
| Consol Partners (Holdings) Limited | Administrative & support | 2014 |
| Consol Partners Limited | Administrative & support | 2007 |
| Consol Solutions Limited | Administrative & support | 2021 |
| Construction & Surveying Limited | Professional & scientific | 2007 |
| Construction Traffic Management Ltd | Professional & scientific | 2023 |
| Construvida Limited | Construction | 2022 |
| Consult Build Limited | Construction | 2006 |
| Consultr Limited | Information & communication | 2018 |
| Conte Transport Ltd | Transport & logistics | 2019 |
| Contemporary Plant Designs Limited | Professional & scientific | 2003 |
| Control 6 Ltd | Information & communication | 2015 |
| Convivia Construction Ltd | Construction | 2017 |
| Cook & SON Limited | Construction | 2008 |
| Cooke & Charman Group Limited | Construction | 2021 |
| Cooke & Charman Limited | Construction | 2018 |
| Cool-Logik Ltd | Manufacturing | 2019 |
| Coolcosy Ltd | Construction | 2009 |
| Cooper Bessant Ltd | Extraterritorial | 2012 |
| Coopers Beach LLP | | 2021 |
| Copthorne Care Homes Ltd | Health & social care | 2021 |
| Copthorne Construction Limited | Construction | 2019 |
| Copthorne Furniture Co. Limited | Wholesale & retail | 1998 |
| Copthorne Golf Club Limited | Hospitality | 2021 |
| Copthorne Golf Club Properties Limited | Real estate | 2021 |
| Copthorne Property Maintenance Ltd | Construction | 2012 |
| Copthorne School Trust Limited | Education | 1976 |
| Copthorne Sports and Community Association Limited | Arts & recreation | 2011 |
| Corby Dental Care Limited | Health & social care | 2010 |
| Corby Imaging Limited | Extraterritorial | 2023 |
| Cord Worldwide Ltd | Information & communication | 2009 |
| Cordell L Limited | Wholesale & retail | 2026 |
| Cordial Corporation Ltd | Transport & logistics | 2025 |
| Core Electrical South Ltd | Construction | 2025 |
| Core Electrical Testing Ltd | Manufacturing | 2025 |
| Core Leisure Limited | Manufacturing | 2022 |
| Cornelius House Limited | Health & social care | 2005 |
| Cornerstone Office Solutions Ltd | Households | 2008 |
| Cornerstone Property Assets Limited | Professional & scientific | 2011 |
| Corporate Accommodation Solutions Limited | Real estate | 2017 |
| Corporate Cleans Ltd | Administrative & support | 2024 |
| Corrie Key Properties Ltd | Real estate | 2025 |
| Cosmopolitan Solutions Ltd | Information & communication | 2017 |
| Costa Design Limited | Construction | 2019 |
| Cotton Xtyle Ltd | Wholesale & retail | 2025 |
| Counterfeit Studio Limited | Other services | 2015 |
| Countertop Impact Ltd | Manufacturing | 2020 |
| County Oak Services Ltd | Wholesale & retail | 2023 |
| County Tree Surgeons Limited | Other services | 2001 |
| Courtneys Beautique Ltd | Other services | 2019 |
| Cove Accountancy Services Limited | Professional & scientific | 2013 |
| Covenant Partners Ltd. | Administrative & support | 2023 |
| Cowdi AL Atria & Roof Structures Limited | | 1990 |
| Coztec 3D Solutions Limited | Professional & scientific | 2013 |
| Cozyabodes Ltd | Hospitality | 2024 |
| Cozzmo Group Ltd | Construction | 2025 |
| CP Change Consulting Limited | Professional & scientific | 2024 |
| CP101 Limited | Administrative & support | 2021 |
| Craft Shapes Limited | Wholesale & retail | 2013 |
| Craftec Paper Limited | Wholesale & retail | 1991 |
| Craigside Enterprises Ltd | Health & social care | 2007 |
| Crain Communications Limited | Information & communication | 1981 |
| Crane's Construction Ltd | Construction | 2020 |
| Cranfield M&E Surveying Ltd | Construction | 2026 |
| Crash & Flow Ltd | Professional & scientific | 2021 |
| Crawley & Gatwick Business Watch Limited | Administrative & support | 2006 |
| Crawley & Gatwick Diamond Cars & Taxis Ltd | Transport & logistics | 2020 |
| Crawley Accident Specialists Ltd | Extraterritorial | 2010 |
| Crawley Accountants Limited | Professional & scientific | 2010 |
| Crawley Beauty Salon Limited | Health & social care | 2011 |
| Crawley Bees Ltd | Manufacturing | 2024 |
| Crawley Cabs Limited | Transport & logistics | 2023 |
| Crawley Car Care Centre Limited | Wholesale & retail | 2011 |
| Crawley Carpentry Services Ltd | Construction | 2008 |
| Crawley Carpet Warehouse Ltd | Wholesale & retail | 2011 |
| Crawley Cars Private Ltd | Transport & logistics | 2024 |
| Crawley Chaudhari Burger Limited | Hospitality | 2023 |