| CJC Gaming Ltd | Information & communication | 2021 |
| CJC Music Ltd | Arts & recreation | 2020 |
| CJD Access Solutions Limited | Construction | 2018 |
| CJI Construction Ltd | Construction | 2025 |
| CJM Construction & Property Services Limited | Construction | 2020 |
| CJM Deliveries Ltd | Transport & logistics | 2025 |
| CJM Partnership Ltd | Professional & scientific | 2022 |
| CJP Consulting Engineers Limited | Professional & scientific | 2003 |
| CJP Engineering Consultants Limited | Professional & scientific | 2003 |
| CJP Event Consulting Ltd | Professional & scientific | 2022 |
| CJP Management Limited | Professional & scientific | 2002 |
| Cjws Developments Limited | Construction | 2024 |
| Cjyr Ltd | Wholesale & retail | 2023 |
| CK Clinical Nutrition Ltd | Education | 2026 |
| CK Retail Avenue Ltd | Wholesale & retail | 2025 |
| CK Retail Benton Ltd | Wholesale & retail | 2024 |
| CK Retail Jackson Ltd | Wholesale & retail | 2024 |
| CK Retail Newcastle Ltd | Wholesale & retail | 2025 |
| CK Richardson Estates Ltd | Real estate | 2025 |
| CK Scientific Ltd | Professional & scientific | 2022 |
| CK Warwick Ltd | Wholesale & retail | 2024 |
| CK21 Consultants LLP | | 2005 |
| CK21 Ltd | Professional & scientific | 2015 |
| Ckay Homes Limited | Real estate | 2023 |
| Ckay Solution Limited | Information & communication | 2019 |
| CKF Solutions Ltd | Manufacturing | 2025 |
| Ckhforensics Limited | Professional & scientific | 2017 |
| Cksw Ltd | Health & social care | 2015 |
| CKW Properties Limited | Real estate | 2018 |
| CKW Trading Limited | Wholesale & retail | 2010 |
| CL Cost Consultants Limited | Professional & scientific | 2012 |
| Cladbros UK Limited | Construction | 2025 |
| Claims Inspection Services Ltd | Financial services | 2016 |
| Claire Brown Surgical Referrals Ltd | Professional & scientific | 2025 |
| Claire Errington Limited | Financial services | 1958 |
| Claire Mawson Consulting Ltd | Professional & scientific | 2019 |
| Clan Groups Services Ltd | Information & communication | 2009 |
| CLAN2020 Developments Ltd | Real estate | 2023 |
| Clara Solutions Limited | Manufacturing | 2019 |
| Claremont News Limited | Wholesale & retail | 2003 |
| Claremont Victoria Joinery Ltd | Manufacturing | 2019 |
| Clarence Gate Residents Management Company Limited | Households | 2023 |
| Clarence Taylor Limited | Real estate | 2020 |
| Clarence Taylor Properties Ltd | Real estate | 2025 |
| Claris D'Cruz Ltd | Professional & scientific | 2018 |
| Clarity Compare Limited | Financial services | 2024 |
| Clarity Filmworks Limited | Information & communication | 2025 |
| Clark & Young Limited | Real estate | 2024 |
| Clark Group Construction Ltd | Construction | 2025 |
| Clark Marine Services Ltd | Other services | 2024 |
| Clark Pearson Funeral Directors Limited | Other services | 2023 |
| Clarke & Carrie Ltd | Health & social care | 2020 |
| Clarke and Mcnall Estates Limited | Real estate | 2024 |
| Clarke Consulting Solutions Ltd | Professional & scientific | 2018 |
| Clarke Mairs Law Limited | Professional & scientific | 2021 |
| Clarks Construction Trade Ltd | Wholesale & retail | 2026 |
| Clarkson (N E) Ltd | Transport & logistics | 2012 |
| Clarkson Events Collabs Limited | Arts & recreation | 2021 |
| Clarkson Leisure Limited | Arts & recreation | 2014 |
| Clarkson Taylor Property Limited | Real estate | 2022 |
| Clarkson Ventures Limited | Real estate | 2017 |
| Clarus Limited | Real estate | 1962 |
| Class Wine Ltd | Hospitality | 2020 |
| Classic Fireplaces (N/E) Limited | Wholesale & retail | 2008 |
| Classic Fireplaces Fitting Ltd | Construction | 2014 |
| Classic Foods NCL Ltd | Hospitality | 2025 |
| Classic STU Limited | Administrative & support | 2021 |
| Classic Twist Ltd | Wholesale & retail | 2015 |
| Classy Competitions Ltd | Arts & recreation | 2026 |
| Classyattire Limited | Wholesale & retail | 2023 |
| Claud Christian Ltd | Professional & scientific | 2019 |
| Claud's Catering Ltd | Manufacturing | 2019 |
| Claude's Classic Haircut Ltd | Other services | 2026 |
| Clavering Enterprises Limited | Transport & logistics | 2025 |
| Clavering House Limited | Real estate | 2010 |
| Clavering Place Limited | Construction | 2021 |
| Clavis IDS Limited | Professional & scientific | 2017 |
| Claypath Development Ltd | Construction | 2021 |
| Clayside Property Investments Limited | Real estate | 1954 |
| Clayton Apartments Limited | Hospitality | 2025 |
| Clayton Chippy Ltd | Hospitality | 2026 |
| Clayton Freehold Ltd | Real estate | 1985 |
| Clayton Lodge Management Limited | Households | 2001 |
| Clayton News 1 Convience Store Ltd | Wholesale & retail | 2022 |
| Clayton Road Properties Limited | Real estate | 2019 |
| CLC Systems Ltd | Information & communication | 2009 |
| Cleadon Consultants Limited | Administrative & support | 2025 |
| Clean AS a Whistle Cleaning Company Limited | Administrative & support | 2020 |
| Clean Construction Ltd | Construction | 2025 |
| Clean Hand Car Wash Ltd | Administrative & support | 2025 |
| Clean on North Ltd | Administrative & support | 2025 |
| Clean Reviews Ltd | Professional & scientific | 2016 |
| Clean Smile Limited | Health & social care | 2016 |
| Cleanbiotix Limited | Professional & scientific | 2020 |
| Cleaner Energy Conversion Ltd | Wholesale & retail | 2025 |
| Cleaning Empire Limited | Administrative & support | 2019 |
| Cleaning Motion NE Ltd | Administrative & support | 2026 |
| Cleaninghausepro Ltd | Administrative & support | 2022 |
| Cleanprepkitchen Limited | Manufacturing | 2021 |
| Cleanroom Build Ltd | Construction | 2023 |