| Conciseuk Ltd | Construction | 2016 |
| Condition Based Maintenance UK Ltd | Professional & scientific | 2012 |
| Confident Labs Limited | Health & social care | 2012 |
| Consult Construct Limited | Professional & scientific | 2012 |
| Consult Holdings Limited | Real estate | 2017 |
| Consult HRB Ltd | Professional & scientific | 2026 |
| Consult LDN Limited | Professional & scientific | 2025 |
| Consult QRD Ltd | Professional & scientific | 2015 |
| Conversaurus Ltd | Professional & scientific | 2024 |
| Cooksditch House Care Ltd | Health & social care | 2017 |
| Cooper House Solar Holdings Limited | Energy | 2014 |
| Cooper House Solar Limited | Energy | 2014 |
| Core Payroll Limited | Professional & scientific | 2023 |
| Core Wellness Studio Ltd | Arts & recreation | 2025 |
| Cornerstone Capital Management Limited | Information & communication | 2020 |
| Cornerstone Integrated Solutions UK Ltd | Information & communication | 2019 |
| Coronado Projects Ltd | Real estate | 2018 |
| Court Colman Solar Limited | Energy | 2013 |
| Courthouse Investment Properties Limited | Real estate | 2024 |
| Courtney Engineering Services Limited | Professional & scientific | 1998 |
| Cousins & Co Plumbing & Electrical Ltd | Construction | 2025 |
| Cowley Contracting Limited | Construction | 2025 |
| Cpds Limited | Education | 2007 |
| Cpgcatering Limited | Hospitality | 2025 |
| Crane & Abel Limited | Professional & scientific | 2021 |
| Creative Sense Community Interest Company | Education | 2025 |
| Creed Outdoor Learning Trust | Health & social care | 2013 |
| Creek Creative Community Interest Company | Arts & recreation | 2008 |
| Crescent Innovations Property LLP | | 2024 |
| Crestline Property & Assets Management Ltd | Real estate | 2025 |
| Crosswind Capital Ltd | Professional & scientific | 2021 |
| Crosswind Innovation Ltd | Professional & scientific | 2021 |
| Crowborough Warren Estate Limited | Professional & scientific | 2005 |
| Ctrose Ltd | Agriculture & fishing | 2026 |
| Cubfield Limited | Health & social care | 1978 |
| Cuckseys and Lowton Limited | Construction | 2019 |
| Culinary Couture Limited | Hospitality | 2026 |
| Culver Farm Produce Limited | Agriculture & fishing | 2003 |
| Cumberland House Property Management Ltd | Households | 2025 |
| Cupcake Heart Limited | Wholesale & retail | 2013 |
| Curvebox Limited | Information & communication | 2013 |
| Customer Experience Analytics Ltd | Information & communication | 2018 |
| Cybrconnect Ltd | Information & communication | 2025 |
| Cyclechic Limited | Wholesale & retail | 2008 |
| D & W Riccini Limited | Agriculture & fishing | 2011 |
| D B Mann Property Ltd | Real estate | 2017 |
| D Chand Limited | Wholesale & retail | 2013 |
| D E and a Academy Limited | Education | 2024 |
| D H Bryant and Partners | | 1995 |
| D&R Demolition Ltd | Construction | 2022 |
| D-Dee’S Day Nursery Limited | Education | 2020 |
| D.Rowe & Sons Ltd | Construction | 2013 |
| Dabbs Pond Limited | Real estate | 2023 |
| Dafs Organisation Ltd | Other services | 2022 |
| Dala Growth Services Ltd | Professional & scientific | 2025 |
| Damp Doctor Sussex Ltd | Administrative & support | 2026 |
| DARI2018 Ltd | Transport & logistics | 2023 |
| Dark Horizon Limited | Extraterritorial | 2021 |
| Darley Scientific Ltd | Professional & scientific | 2020 |
| Dave Petty Consultancy Limited | Professional & scientific | 2025 |
| David Paul - Property Limited | Construction | 2013 |
| David Rumsey Dressage Ltd | Agriculture & fishing | 2012 |
| Davies Interiors Ltd | Manufacturing | 2024 |
| Dawson Stone Limited | Manufacturing | 2021 |
| Dayone Design Kent Ltd | Professional & scientific | 2021 |
| DBDRIVES63 Ltd | Transport & logistics | 2022 |
| DC Medical Consulting Ltd | Administrative & support | 2023 |
| DCS Kent Ltd | Construction | 2022 |
| Ddurkin Limited | Professional & scientific | 2026 |
| Deehaven Farms Ltd | Agriculture & fishing | 1981 |
| Dekor Limited | Wholesale & retail | 2017 |
| Deliver Digital Ltd | Professional & scientific | 2019 |
| Dello Data Analytics Limited | Information & communication | 2021 |
| Demorian Limited | Information & communication | 2015 |
| Denly Consulting Limited | Professional & scientific | 2016 |
| Dent Tricks UK Ltd | Wholesale & retail | 2024 |
| Deposit Replacement Scheme Ltd | Hospitality | 2019 |
| Devised Carpentry Ltd | Manufacturing | 2026 |
| Dewatts Consulting Ltd | Professional & scientific | 2013 |
| Dewatts Homes Ltd | Real estate | 2026 |
| Dfinch Limited | Professional & scientific | 2022 |
| DFM Property Management Kent Ltd | Real estate | 2025 |
| DHC House Services Ltd | Administrative & support | 2023 |
| DHP Advisors Ltd | Professional & scientific | 2020 |
| DI White Construction Ltd | Construction | 2025 |
| Diamond Carpentry & Building Services Limited | Construction | 2023 |
| Diane Porteous Ltd | Construction | 2007 |
| Dig!Tal Limited | Professional & scientific | 2019 |
| Digital Web Presence Ltd | Information & communication | 2024 |
| Dilligan Ltd | Wholesale & retail | 2025 |
| Dinc 68 Limited | Hospitality | 2018 |
| Dingo Limited | Manufacturing | 2021 |
| Diva Metalwork Limited | Manufacturing | 1999 |
| Diztinct Limited | Professional & scientific | 2010 |
| DLB Films Ltd | Information & communication | 2025 |
| Dmws Property Maintenance Ltd | Construction | 2021 |
| Dockeray Feeds Limited | Agriculture & fishing | 2011 |
| Dominion Faith Ministry Limited | Professional & scientific | 2021 |
| Dominion Logic Services Ltd | Administrative & support | 2021 |
| Dominion Properties UK Limited | Real estate | 2024 |