| Crumbs Trading Limited | Hospitality | 2007 |
| CRW 03 Limited | Real estate | 1990 |
| Crystal Cleaners Limited | Wholesale & retail | 2020 |
| Crystalight Elevate Ltd | Wholesale & retail | 2023 |
| Crystaltech Southwest Limited | Construction | 2025 |
| CS Events Ltd | Administrative & support | 2022 |
| CS Frequency Limited | Information & communication | 2015 |
| CS Frequency Property Limited | Real estate | 2024 |
| CS Garden Solutions Ltd | Administrative & support | 2021 |
| CSC Cleaning Solutions Contractors Ltd | Administrative & support | 2018 |
| CSG Staffing Limited | Wholesale & retail | 2021 |
| CSL Developments Limited | Manufacturing | 1997 |
| Cslw Consulting Limited | Professional & scientific | 2013 |
| CSM Housing Ltd | Real estate | 2021 |
| Csmsoftware Consultancy Ltd | Information & communication | 2012 |
| CSO Alliance Limited | Administrative & support | 2012 |
| CT Excellence Football Academy Ltd | Arts & recreation | 2024 |
| Ctek Cleaning Ltd | Administrative & support | 2025 |
| CTG Pathology Limited | Health & social care | 2025 |
| CTH 2016 Ltd | Transport & logistics | 2016 |
| CTS Property Group Ltd | Construction | 2019 |
| Cube Studios Ltd | Administrative & support | 1998 |
| Cubio Ltd | Professional & scientific | 2025 |
| Cublington Walled Gardens Management Company Limited | Households | 2011 |
| Cuckoo Recruiter Limited | Professional & scientific | 2020 |
| Cuivienql Ltd | Information & communication | 2017 |
| Cullen Conservation Limited | Professional & scientific | 2017 |
| Cuoshi Ltd | Information & communication | 2014 |
| Curantis 365 Ltd | Health & social care | 2019 |
| Curiosity Coffee Ltd | Manufacturing | 2018 |
| Curodito Limited | Administrative & support | 2012 |
| Currencyhome Limited | Professional & scientific | 2018 |
| Current Vision Limited | Professional & scientific | 2011 |
| CUT & Carve Carpentry Ltd | Construction | 2025 |
| Cutler Management Limited | Professional & scientific | 2001 |
| Cutlers Close Management Company Limited | Extraterritorial | 1992 |
| Cutlist Limited | Manufacturing | 2015 |
| Cuts R US Limited | Other services | 2005 |
| Cuttered Toast Limited | Professional & scientific | 2026 |
| Cutts Interiors Limited | Construction | 2019 |
| CVC Services Ltd | Health & social care | 2021 |
| CW Technical Services Ltd | Construction | 2025 |
| Cwat Professional Services Limited | Education | 2026 |
| Cwheatserve Ltd | Construction | 2015 |
| CXC Group Limited | Information & communication | 2023 |
| Cybacor Ltd | Information & communication | 2015 |
| Cyber Logistics Limited | Information & communication | 2002 |
| Cyber Security Protection Alliance Limited | Information & communication | 2010 |
| Cyber Tech AI Solutions Ltd | Information & communication | 2025 |
| Cygnos Limited | Information & communication | 1999 |
| Cygnus Manufacturing Limited | Manufacturing | 2020 |
| Czam Stores Limited | Wholesale & retail | 2020 |
| D & H Saunders Ltd | Construction | 2020 |
| D & M Foods Delivery Ltd | Wholesale & retail | 2026 |
| D Alexa Ltd | Construction | 2018 |
| D D H Consultants Limited | Professional & scientific | 1987 |
| D D Radford Ltd | Administrative & support | 2026 |
| D Evans PS Limited | Construction | 2022 |
| D G Electrical Solutions Limited | Construction | 2018 |
| D Johnston Heating & Plumbing Solutions Ltd | Construction | 2023 |
| D M J Express Ltd | Transport & logistics | 2010 |
| D Mcqueen Limited | Health & social care | 2024 |
| D Quilter Ltd | Agriculture & fishing | 2014 |
| D Straszak Limited | Transport & logistics | 2026 |
| D Tuley Carpentry and Building Ltd | Construction | 2023 |
| D&D DC Properties Ltd | Real estate | 2025 |
| D&K Restorations Ltd | Manufacturing | 2019 |
| D&R Housing Solutions Ltd | Real estate | 2024 |
| D.A.D.S Electrical Services Limited | Construction | 2026 |
| D.I.R Ltd | Construction | 2016 |
| D2F Holdings Ltd | Financial services | 2021 |
| D2S Software Limited | Wholesale & retail | 2014 |
| D30 Properties Ltd | Real estate | 2026 |
| D4 Medics Limited | Health & social care | 2021 |
| DA Vincis Pencil Limited | Extraterritorial | 2016 |
| Dabt Property Ltd | Real estate | 2025 |
| DAC Removals and Storage Limited | Transport & logistics | 2015 |
| Dadbrook Farm Limited | Agriculture & fishing | 2020 |
| Dadwin Healthcare Ltd | Health & social care | 2021 |
| Dage Holdings Limited | Professional & scientific | 1997 |
| Dage Pension Trustees Limited | Professional & scientific | 2005 |
| Dage Precision Industries Limited | Manufacturing | 1992 |
| DAI Services Ltd | Other services | 2019 |
| Dail Consulting Ltd | Professional & scientific | 2011 |
| Dail Properties Ltd | Real estate | 2016 |
| Dala International Limited | Other services | 2019 |
| Dalchini Wendover Ltd | Hospitality | 2025 |
| Dalesford Plumbing & Heating Limited | Other services | 2002 |
| Daliani Boutique (Hitchin) Ltd | Wholesale & retail | 2024 |
| Daly Rodents Limited | Agriculture & fishing | 2016 |
| Damp Surveyors Ltd | Construction | 2024 |
| DAN Burch Creative Ltd | Administrative & support | 2025 |
| DAN Pullen Hire and Haulage Ltd | Transport & logistics | 2021 |
| Danai Limited | Health & social care | 2018 |
| Danard Ltd | Professional & scientific | 2018 |
| Daniel Burke Limited | Arts & recreation | 2011 |
| Danny Livett Limited | Construction | 2014 |
| Danny Rickard Limited | Information & communication | 2023 |
| Dansy Ventures Limited | Professional & scientific | 2022 |
| Danton Associates Limited | Professional & scientific | 2019 |