| Concorde Industries Limited | Extraterritorial | 1973 |
| Connect-I Media Limited | Information & communication | 2019 |
| Contemporis Investments Limited | Financial services | 2024 |
| Conway Family Care Ltd | Health & social care | 2026 |
| Cook Farms Limited | Agriculture & fishing | 2014 |
| Copy Masterclass Ltd | Education | 2021 |
| COR Care Force Ltd | Transport & logistics | 2019 |
| Corequantlogicnetai Ltd | Information & communication | 2026 |
| Coria Intelligence and Security Limited | Professional & scientific | 2018 |
| Cornwell Plumbing & Developments Ltd | Construction | 2024 |
| Corrie Sellers Ltd | Professional & scientific | 2024 |
| Cosanti Limited | Information & communication | 2007 |
| Coscaris Limited | Real estate | 2018 |
| Count Five Ltd | Professional & scientific | 2015 |
| Courthouse Mews Limited | Real estate | 2003 |
| CPC Laws Ltd | Other services | 2018 |
| Craf Management Consultants Ltd | Professional & scientific | 2019 |
| Craft Hospitality Limited | Hospitality | 2020 |
| Crawley Grange Residents Association Limited | Households | 1977 |
| Creative Accountancy Limited | Professional & scientific | 2010 |
| Creative Flooring (Milton Keynes) Limited | Construction | 1997 |
| Credit Collection Consultants Limited | Extraterritorial | 1991 |
| Crest Developments Southern Limited | Administrative & support | 2019 |
| Crmk CIC | Information & communication | 2017 |
| Cross Keys PUB Limited | Extraterritorial | 2016 |
| Crowborough Images Limited | Arts & recreation | 2019 |
| Cruagh Ltd | Construction | 2022 |
| Crumb Cookies Ltd | Manufacturing | 2023 |
| CSM Building Surveyors Ltd | Professional & scientific | 2024 |
| CTA Facilities Limited | Hospitality | 2010 |
| CTB Audio Limited | Manufacturing | 2019 |
| CTF Scaffolding Ltd | Construction | 2024 |
| Cwtch & Collect Ltd | Wholesale & retail | 2023 |
| D a V Builders Ltd | Construction | 2019 |
| D C Eades Farriery Limited | Agriculture & fishing | 2009 |
| D K Heating Services Limited | Construction | 2021 |
| D P Photographic Services Limited | Professional & scientific | 2012 |
| D&S Training Solutions Ltd | Professional & scientific | 2024 |
| Daltons BA Ltd | Professional & scientific | 2013 |
| Dama Engineering Consultants Limited | Professional & scientific | 2024 |
| Damian Russell Photography Limited | Professional & scientific | 2013 |
| Damm Advisory Ltd | Information & communication | 2025 |
| Dandi Auto Deliveries Ltd | Transport & logistics | 2024 |
| Dandid Ltd | Information & communication | 2013 |
| Dappa Limited | Wholesale & retail | 2025 |
| Darkloop Technologies Ltd | Wholesale & retail | 2026 |
| Datagravity Ltd | Information & communication | 2021 |
| David Pearson Advertising Limited | Professional & scientific | 1993 |
| Dbab Limited | Other services | 2021 |
| Dbanart Limited | Professional & scientific | 2025 |
| DBN Headhunters Ltd | Administrative & support | 2020 |
| DC Fibre Limited | Information & communication | 2023 |
| DCC Interactive Limited | Professional & scientific | 2020 |
| Dcmd Electrics Ltd | Construction | 2012 |
| DE Novo Partners Limited | Professional & scientific | 2013 |
| Dealcore Property Sourcing Ltd | Real estate | 2026 |
| Deep Clean Services Limited | Extraterritorial | 1998 |
| Deep Purple Live Limited | Other services | 2019 |
| Deerwalk Properties Limited | Real estate | 1994 |
| Deliver, Grow Ltd | Professional & scientific | 2017 |
| Denara Property Ltd | Real estate | 2013 |
| Denara Property Sourcing Ltd | Real estate | 2020 |
| Denton Mews Gardens Limited | Households | 1994 |
| Dependable Power Ltd | Professional & scientific | 2026 |
| Derwent House RTM Company Limited | Households | 2012 |
| Design Daniels Limited | Information & communication | 2008 |
| Deslan Consultants Ltd | Real estate | 2002 |
| Dessert MK IP Limited | Hospitality | 2023 |
| Devlin Dynamic Solutions Limited | Financial services | 2025 |
| DHB MK Lettings Limited | Real estate | 2021 |
| Diamond Dental MK Ltd | Health & social care | 2022 |
| Diamonds Carpet Services Limited | Wholesale & retail | 2018 |
| Digihealthit Consulting & Professional Services Limited | Professional & scientific | 2023 |
| Digiruu Ltd | Information & communication | 2016 |
| Digistain Limited | Professional & scientific | 2019 |
| Digital & General Publishing London Limited | Information & communication | 2012 |
| Digital Marketing Engine Limited | Professional & scientific | 2018 |
| Digsby Limited | Administrative & support | 2011 |
| Distribution on Time Ltd | Transport & logistics | 2023 |
| Dixton Investments Limited | Real estate | 2020 |
| DJ Gear.Co.Uk Limited | Professional & scientific | 2003 |
| DJB Labcare Limited | Manufacturing | 2005 |
| DJKAY2 Events Limited | Arts & recreation | 2017 |
| Dkld Services Ltd | Information & communication | 2022 |
| DLS Security Limited | Administrative & support | 2011 |
| Dodman Hospitality Limited | Wholesale & retail | 2015 |
| Dollars Grove Farms Limited | Professional & scientific | 2012 |
| Dolphin PUB Newport Pagnell Ltd | Hospitality | 2025 |
| Domdom Ltd | Manufacturing | 2019 |
| Donlon Management & Security Services Limited | Administrative & support | 2010 |
| Dorling Builders Ltd | Construction | 2016 |
| Double Sleeved Limited | Wholesale & retail | 2019 |
| Dougie's Garden Services Limited | Other services | 2017 |
| Dowmans Barns Ltd | Construction | 2020 |
| Dowmans TIN Barns Ltd | Construction | 2020 |
| DP Live LLP | | 2019 |
| DP Smart Home Ltd | Wholesale & retail | 2021 |
| DR Arjun Patel Limited | Health & social care | 2022 |
| Dragonfern Mowing Co Ltd | Administrative & support | 2026 |
| Dream Home Experts Ltd | Construction | 2016 |