| Composing Copy LLP | | 2017 |
| Comtrans Travel Ltd | Transport & logistics | 2008 |
| Comunidade Europeia DE Trafego Ltd | Manufacturing | 2021 |
| Concept Housewares Ltd | Wholesale & retail | 2003 |
| Concierge Travel and Tours UK Ltd | Hospitality | 2020 |
| Conco Plumbing & Heating Ltd | Construction | 2016 |
| Conection Limited | Construction | 2018 |
| Confidental Clinic Ltd | Health & social care | 2007 |
| Confinet Professional Services Ltd | Information & communication | 2016 |
| Conformity Certification Services Ltd | Administrative & support | 2013 |
| Conmich Limited | Professional & scientific | 2009 |
| Connaught Home Interiors Limited | Construction | 2014 |
| Connect Interservice Ltd | Transport & logistics | 2016 |
| Connect Right Ltd | Wholesale & retail | 2023 |
| CONNECT-TECH3 Ltd | Other services | 2022 |
| Connectatherapy Ltd | Health & social care | 2019 |
| Connectco Limited | Information & communication | 2023 |
| Connections Consult Ltd | Information & communication | 2022 |
| Connectly Ltd | Information & communication | 2024 |
| Conoscenti & Fine Ltd | Wholesale & retail | 2019 |
| Conpac Limited | Administrative & support | 2020 |
| Conquering Lion Muzick Ltd | Information & communication | 2020 |
| Consensus Facilities Management Ltd | Water & waste | 2025 |
| Conservatory Roofs 4 YOU Ltd | Construction | 2021 |
| Consolidated Imex Limited | Transport & logistics | 1981 |
| Constantbay Limited | Real estate | 2021 |
| Constantin Rusu Limited | Transport & logistics | 2019 |
| Construction Community Ltd | Professional & scientific | 2012 |
| Construire Services Limited | Construction | 2020 |
| Consult Micro Guru Limited | Health & social care | 2023 |
| Consultancy and Audit Limited | Other services | 2019 |
| Consulting Engineering Group Ltd | Construction | 2024 |
| Cont Transport Ltd | Construction | 2019 |
| Contemporary Collection CC Ltd | Wholesale & retail | 2023 |
| Convergence Trust | Education | 2020 |
| Convertibles Driving School Limited | Education | 2023 |
| Convertway Ltd | Construction | 2022 |
| Convex Advertising Limited | Other services | 2025 |
| Cook House Ltd | Wholesale & retail | 2025 |
| Cool Freeze and Heating Ltd | Construction | 2026 |
| Cool Vantage Ltd | Wholesale & retail | 2023 |
| Copper Kadai Limited | Hospitality | 2023 |
| Copperfield Rise Limited | Real estate | 2025 |
| Corberrie Construction Limited | Wholesale & retail | 1984 |
| Corbrig Limited | Other services | 2018 |
| Cordoba Holdings Limited | Real estate | 2024 |
| Cordoba Research and Innovation Ltd | Information & communication | 2024 |
| Cordoba Venture Studio Ltd | Information & communication | 2024 |
| Core Care Services Ltd | Administrative & support | 2020 |
| Core Developers Limited | Real estate | 2017 |
| Core Intelligence Ltd | Information & communication | 2025 |
| Core Telecom Europe Ltd | Information & communication | 2023 |
| Coreparts Distribution Ltd | Wholesale & retail | 2026 |
| Corevixa Ltd | Wholesale & retail | 2026 |
| Corex Retail Solutions Ltd | Wholesale & retail | 2025 |
| Corja Construction Ltd | Construction | 2023 |
| Corner Shop Food & Wine Ltd | Wholesale & retail | 2013 |
| Cornerstone Community Care and Training Centre Ltd | Health & social care | 2021 |
| Cornerstone Decor&Paint Ltd | Construction | 2025 |
| Coromandel Foods Limited | Hospitality | 2018 |
| Corporate Benefits Limited | Arts & recreation | 2015 |
| Corpstop Limited | Real estate | 2024 |
| Corwins Limited | Real estate | 2013 |
| Cosgrove House Management Company Limited | Extraterritorial | 2014 |
| Cosmic Healthcare Ltd | Wholesale & retail | 2014 |
| Cosmos Enterprises International Ltd | Information & communication | 2016 |
| Costa Consultancy Ltd | Professional & scientific | 2021 |
| Costa Impex Ltd | Construction | 2017 |
| Costantin Dumitreasa Ltd | Transport & logistics | 2021 |
| Costcut Consultants Ltd | Construction | 2024 |
| Costgroup Ltd | Construction | 2017 |
| Costless Construction Limited | Construction | 2023 |
| Costume Designs UK Limited | Manufacturing | 2004 |
| Cosy Yoga Ltd | Information & communication | 2025 |
| COSYPRO24 Ltd | Wholesale & retail | 2024 |
| Cottage Chicken and Pizza Ltd | Hospitality | 2017 |
| Cottage Clinic Limited | Health & social care | 2012 |
| Cottington 50 (UK) Limited | Households | 2003 |
| Cotton and Cottage Care Ltd | Health & social care | 2026 |
| Coulm Ecom Ltd | Wholesale & retail | 2021 |
| Country MAT Limited | Real estate | 2020 |
| Covax Investments Limited | Real estate | 2002 |
| Covenant Estates Ltd | Real estate | 2025 |
| Covent Square Limited | Real estate | 2023 |
| Covert Security Limited | Administrative & support | 2014 |
| Cozynestsupplies Ltd | Wholesale & retail | 2025 |
| CP200 Ltd | Professional & scientific | 2011 |
| CPD Estates Ltd | Extraterritorial | 2008 |
| CPL Audit Ltd | Professional & scientific | 1999 |
| Cradle Studios Ltd | Information & communication | 2017 |
| Craft Management Services Limited | Real estate | 2019 |
| Cranbrook 25 Ltd | Real estate | 2025 |
| Cranbrook Chauffeurs Ltd | Transport & logistics | 2026 |
| Cranbrook Electrics Limited | Wholesale & retail | 2021 |
| Cratus Business Center Ltd | Administrative & support | 2025 |
| Crawford BS Limited | Construction | 2018 |
| Crawley Fish and Chips Ltd | Hospitality | 2026 |
| Crazy Accessories Ltd | Wholesale & retail | 2024 |
| Crazy Builder Ltd | Construction | 2025 |
| Crazyworld Ltd | Wholesale & retail | 2024 |