| Collections by MS Ltd | Wholesale & retail | 2026 |
| Collective 3 Group Limited | Other services | 2017 |
| Collett Advisory Limited | Professional & scientific | 2026 |
| Collett Property Company Limited | Real estate | 2021 |
| Collingdon Court Freehold Limited | Real estate | 2012 |
| Colour Tuning Ltd | Wholesale & retail | 2020 |
| Colson Company (UK) Limited | Transport & logistics | 2014 |
| Coltron Computers Limited | Other services | 2014 |
| Coman Transport Ltd | Transport & logistics | 2023 |
| Combi Solutions Limited | Construction | 2009 |
| Combined Capital Properties Ltd | Real estate | 2024 |
| Comelit-Pac Limited | Manufacturing | 2001 |
| Comensura Limited | Professional & scientific | 2000 |
| Comfort Auto Parts Ltd | Wholesale & retail | 2024 |
| Comfort Care Ltd | Health & social care | 2025 |
| Comfort Sleep Ltd | Wholesale & retail | 2003 |
| Comfort Sleep Zone Ltd | Wholesale & retail | 2018 |
| Comfort Toilet Hire Limited | Water & waste | 2021 |
| Comfort Zone Care Services Ltd | Health & social care | 2016 |
| Commerce Domain Ltd | Wholesale & retail | 2024 |
| Commercial ARC Ltd | Wholesale & retail | 2026 |
| Commercial Improvements Limited | Construction | 2018 |
| Commercial Land Estates Limited | Real estate | 2016 |
| Commercial Properties Investment Ltd | Real estate | 2022 |
| Commercial Properties London Limited | Real estate | 2025 |
| Commoncrest Ltd | Real estate | 2009 |
| Commonside Solutions Limited | Information & communication | 2007 |
| Communicate Well Limited | Education | 2004 |
| Community Action Bedfordshire (Trading) Ltd | Hospitality | 2019 |
| Community Development and Growth CIC | Education | 2022 |
| Community Interest Luton CIC | Health & social care | 2013 |
| Community IS Strength Ltd | Arts & recreation | 2025 |
| Community Needs Ltd | Education | 2011 |
| Community Needs Luton CIC | Education | 2024 |
| Community Pubs Foundation | Hospitality | 2005 |
| Community Training Portal Limited | Education | 2004 |
| Company for ME Ltd | Administrative & support | 2012 |
| Compare Tech Solutions Ltd | Information & communication | 2026 |
| Compass Management Limited | Households | 2020 |
| Compass Motors Ltd | Wholesale & retail | 2024 |
| Competition Engine Services Limited | Wholesale & retail | 2015 |
| Complete Civil Engineer Limited | Construction | 2009 |
| Complete Medical Ltd | Health & social care | 2022 |
| Complete Security Solutions (UK) Limited | Administrative & support | 2004 |
| Completehealthcaresols Ltd | Wholesale & retail | 2023 |
| Complex Care Quality Ltd | Health & social care | 2026 |
| Complex Lofts Ltd | Construction | 2025 |
| Complex Properties Limited | Real estate | 2025 |
| Compose Ltd | Health & social care | 2024 |
| Comprehensive Systems Control Limited | Professional & scientific | 2011 |
| Compro Consultants Ltd | Information & communication | 2017 |
| Compton GAS and Garden Centre Limited | Wholesale & retail | 2010 |
| Computer Forge Limited | Information & communication | 2017 |
| Computer Services & Software Limited | Information & communication | 2000 |
| Comsell Limited | Wholesale & retail | 2026 |
| CON Infra COM Ltd | Construction | 2019 |
| Conache Services Limited | Construction | 2023 |
| Conad Limited | Construction | 2025 |
| Conaf Ltd | Construction | 2023 |
| Concrete Masters Ltd | Construction | 2014 |
| Concrete Repair Solutions Ltd | Construction | 2025 |
| Concrete, Block and Beam Specialists (C.B.B.S) Limited | Construction | 2024 |
| Condell’S Consultancy Ltd | Professional & scientific | 2019 |
| Condor Estates Management Limited | Real estate | 2025 |
| Confectionary Traders Limited | Wholesale & retail | 2017 |
| Confey Civils Ltd | Construction | 2023 |
| Confidence Care Ltd | Information & communication | 2019 |
| Confluence Care Services Limited | Public administration | 2024 |
| Conifer Holdings Limited | Financial services | 2020 |
| Connaught Mini Buses Ltd | Transport & logistics | 2023 |
| Connear Ltd | Information & communication | 2024 |
| Connect Provider Limited | Administrative & support | 2016 |
| Connect Seven Ltd | Information & communication | 2022 |
| Connect XP Limited | Information & communication | 2022 |
| Connectrasec Limited | Information & communication | 2025 |
| Connoisseur Resources UK Ltd | Administrative & support | 2022 |
| Connolly Homes Limited | Construction | 1963 |
| Connor Bros. Surfacing Ltd | Construction | 2024 |
| Conquest Investments Limited | Real estate | 2006 |
| Considine Motor Services Ltd | Wholesale & retail | 2003 |
| Constantinluktrans Limited | Transport & logistics | 2019 |
| Constantinobuilding Limited | Manufacturing | 2024 |
| Constelation Services Ltd | Other services | 2025 |
| Construcore Limited | Information & communication | 2023 |
| Construct and Renovation LTN Ltd | Construction | 2025 |
| Construct and Renovation RIK Ltd | Construction | 2025 |
| Construction and Interior Designing Limited | Professional & scientific | 2025 |
| Construction C&S Limited | Construction | 2024 |
| Construction Training (B&H) Limited | Education | 1991 |
| Constructions Art Limited | Wholesale & retail | 2021 |
| Consultant 84 Ltd | Construction | 2021 |
| Consulting DO LLP | | 2023 |
| Consulting Services MK Limited | Administrative & support | 2015 |
| Contax Support Limited | Professional & scientific | 2017 |
| Contractorcompany Ltd | Households | 2021 |
| Contractorpipeline Ltd | Professional & scientific | 2026 |
| Contrax PAY Ltd | Administrative & support | 2019 |
| Controls Comm Limited | Construction | 2010 |
| Convoshopper Ltd | Wholesale & retail | 2022 |
| Conway Health Care Services Ltd | Administrative & support | 2020 |