| Connault House Management Company Limited | Administrative & support | 2010 |
| Connolly & SON Developments Limited | Construction | 2024 |
| Connolly & SON Limited | Construction | 2018 |
| Connolly and SON Lettings Limited | Real estate | 2024 |
| Construct Carpentry Limited | Manufacturing | 2026 |
| Contracting Innovation IP Limited | Administrative & support | 2018 |
| Conveneworks Ltd | Wholesale & retail | 2009 |
| Convenient Properties Ltd | Real estate | 2022 |
| Convergence Cyber & AI Ltd | Information & communication | 2025 |
| Cool AS Frost Limited | Construction | 2021 |
| Coopers Close Residents Management Company Ltd | Households | 2026 |
| Coopers Mill Limited | Health & social care | 2002 |
| Coopers Transport Services Limited | Transport & logistics | 2008 |
| Copest Limited | Wholesale & retail | 2018 |
| Copper Club Limited | Real estate | 2023 |
| Copper Holdings Limited | Financial services | 2021 |
| Copper Lookout Limited | Real estate | 2024 |
| Coppertub Property Ltd | Real estate | 2024 |
| Cordercare Ltd | Health & social care | 2012 |
| Core Connect Education Limited | Education | 2025 |
| Core Technology Projects Ltd | Wholesale & retail | 2003 |
| Corepack Limited | Administrative & support | 2017 |
| Cosy Creations Ltd | Wholesale & retail | 2025 |
| Cotcord Ltd | Manufacturing | 2020 |
| Cottrill Holdings Limited | Financial services | 2009 |
| Countrywide Developments Limited | Real estate | 2014 |
| Countrywide Produce Limited | Wholesale & retail | 2002 |
| Coyote Bar and Diner Limited | Hospitality | 2019 |
| CPM Carpentry & Joinery Ltd | Manufacturing | 2022 |
| Crescence Nursing & Support Services Ltd | Health & social care | 2025 |
| Crimsyn Group Holdings Ltd | Financial services | 2019 |
| Crisp Aerospace Consultants Ltd | Professional & scientific | 2025 |
| Crisp HR Solutions Limited | Administrative & support | 2025 |
| Crosby Roofing Services Ltd | Construction | 2017 |
| Cross Country RV Ltd | Wholesale & retail | 2013 |
| Crossfit Structure Ltd | Arts & recreation | 2021 |
| Crown House Close Property Management Company Limited | Households | 2005 |
| Crowsons Motors Limited | Wholesale & retail | 2014 |
| Crystal Computers Limited | | 2001 |
| CS Engineering Ltd | Professional & scientific | 2018 |
| CS Medical Support Limited | Health & social care | 2025 |
| CS Young Construction Ltd | Construction | 2016 |
| Cslj Ltd | Administrative & support | 2017 |
| Culture Trading Ltd | Wholesale & retail | 2020 |
| Cumulatus Ltd | Information & communication | 2017 |
| Curson Electrical Limited | Construction | 2016 |
| Curson Homes Ltd | Construction | 2012 |
| Curtainique Limited | Manufacturing | 2011 |
| Cutting Edge VEG Limited | Manufacturing | 2024 |
| CWC Sales & Marketing Ltd | Professional & scientific | 2024 |
| CWG Groundworks Limited | Construction | 2018 |
| Cwtechnology Ltd | Information & communication | 2026 |
| D & D Builders LLP | | 2017 |
| D & I Plumbing & Heating Limited | Construction | 2015 |
| D & J Wadsley Limited | Agriculture & fishing | 2022 |
| D & L Co. Ltd. | Health & social care | 2011 |
| D E Downham Haulage Limited | Transport & logistics | 2003 |
| D H Fenland Limited | Professional & scientific | 2006 |
| D Hyde Construction Ltd | Construction | 2020 |
| D J and a Lunn Ltd | Agriculture & fishing | 2014 |
| D Norris Construction Limited | Construction | 2025 |
| D P Reinforcement Ltd | Construction | 2018 |
| D Pedley Construction Limited | Construction | 2019 |
| D R a Fabb (Holdings) Limited | Financial services | 2020 |
| D R a Fabb Construction Limited | Construction | 2005 |
| D R a Fabb Contractors Limited | Agriculture & fishing | 2007 |
| D R a Fabb Hire Limited | Administrative & support | 2020 |
| D Timbrell Limited | Manufacturing | 2017 |
| D&A Mini Plant Ltd | Administrative & support | 2020 |
| D&E Windows & Doors Ltd | Manufacturing | 2022 |
| D&G Connections Ltd | Transport & logistics | 2023 |
| D'Avekki Holdings Limited | Professional & scientific | 2019 |
| D'Avekki Studios Limited | Wholesale & retail | 2003 |
| D.G & K.G Property Ltd | Real estate | 2024 |
| D.G.Bullard Limited | Agriculture & fishing | 1957 |
| D.H. Arrowsmith Properties Limited | Real estate | 2006 |
| DA Performance Engineering Limited | Wholesale & retail | 2020 |
| Da-Mar Engineering (Leicester) Limited | Manufacturing | 2002 |
| Dafen Ground Rents Limited | Real estate | 2021 |
| Dafen UK Limited | Financial services | 2024 |
| Dainty Designs Ltd | Manufacturing | 2023 |
| Dale Insulated Doors Limited | Professional & scientific | 2008 |
| Dale Sheetmetal Holdings Limited | Financial services | 2023 |
| Damien's Driving School Ltd | Education | 2019 |
| DAN Hill Catering Equipment Services Ltd | Wholesale & retail | 2019 |
| DAN Wright Property Ltd | Real estate | 2024 |
| Daniel&Co. Limited | Agriculture & fishing | 2023 |
| Danov Transport Ltd | Transport & logistics | 2026 |
| DAR Parts Limited | Wholesale & retail | 2017 |
| Darkweb Limited | Wholesale & retail | 2020 |
| Darrel Else Furnishers Limited | Wholesale & retail | 1965 |
| Daumar Limited | Administrative & support | 2010 |
| Dave Parrin Car Sales Limited | Wholesale & retail | 2025 |
| Dave Rayner Commercials Limited | Wholesale & retail | 2006 |
| Davenport Clarke Limited | Construction | 2015 |
| David Pritchard Limited | Construction | 2014 |
| David Sanderson Ltd | Agriculture & fishing | 2006 |
| Davidcathy Ltd | Real estate | 2020 |
| Davis Squared Limited | Professional & scientific | 2024 |
| Daw-Build Limited | Construction | 2020 |