| CT Sancta Ltd | Health & social care | 2019 |
| CT Signalling Ltd | Construction | 2025 |
| Ct&Y Consultancy Limited | Information & communication | 2024 |
| CT1 Finance Limited | Financial services | 2018 |
| CTA 365 Limited | Administrative & support | 2012 |
| CTA Design Ltd | Other services | 2016 |
| CTA Healthcare Ltd | Health & social care | 2024 |
| CTA Property Investments Ltd | Real estate | 2024 |
| CTA Studios Limited | Manufacturing | 2025 |
| CTA Trading Limited | Other services | 1993 |
| Ctbd Consulting (UK) Limited | Professional & scientific | 2023 |
| CTC Academy Limited | Education | 2022 |
| CTC International | Health & social care | 2017 |
| Ctclinic.Co.Uk Limited | Health & social care | 2015 |
| Ctee Nannies Limited | Health & social care | 2024 |
| CTH Accommodations Ltd | Hospitality | 2022 |
| CTI Digital Limited | Information & communication | 2003 |
| CTI Holdings Limited | Information & communication | 2018 |
| CTI Investments Limited | Financial services | 2020 |
| CTL Estates (Management) Ltd | Real estate | 2012 |
| CTL Estates Ltd | Extraterritorial | 2002 |
| CTL Projects Ltd | Information & communication | 2016 |
| Ctldarkroom Ltd | Professional & scientific | 2024 |
| CTM Web Ltd | Transport & logistics | 2022 |
| Ctmantra Ltd | Construction | 2025 |
| Ctml Group Ltd | Wholesale & retail | 2022 |
| Ctml Limited | Wholesale & retail | 2008 |
| CTN Management Limited | Extraterritorial | 2021 |
| CTO Polyolefins UK Limited | Manufacturing | 2025 |
| CTO Scope Limited | Information & communication | 2025 |
| CTR Joinery (NW) Limited | Construction | 2017 |
| CTR Site Services Limited | Construction | 2017 |
| Ctrl ALF Delete Limited | Professional & scientific | 2023 |
| Ctrl ALT Sports Ltd | Arts & recreation | 2025 |
| Ctrl Records Limited | Administrative & support | 2014 |
| Ctrl Sport Ltd | Education | 2017 |
| Ctronic Ltd | Wholesale & retail | 2018 |
| CTS Property Holdings Ltd | Real estate | 2025 |
| CTS Services Group Ltd | Administrative & support | 2025 |
| Ctsl Spill Specialists Limited | Manufacturing | 2018 |
| Ctwp Ltd | Professional & scientific | 2024 |
| CTY Property Ltd | Real estate | 2023 |
| CU Payments Ltd | Wholesale & retail | 2023 |
| CU Plumbing and Heating (Yorkshire) Ltd | Construction | 2025 |
| CU Properties Limited | Real estate | 2002 |
| Cu-Piping Limited | Construction | 2009 |
| Cuadrilla Balcombe Limited | Mining & quarrying | 2009 |
| Cuadrilla Bowland Limited | Mining & quarrying | 2012 |
| Cuadrilla Elswick (NO.2) Limited | Mining & quarrying | 2010 |
| Cuadrilla Elswick Limited | Mining & quarrying | 2009 |
| Cuadrilla Gainsborough Limited | Mining & quarrying | 2016 |
| Cuadrilla North Cleveland Limited | Mining & quarrying | 2016 |
| Cuadrilla Resources Holdings Limited | Professional & scientific | 2010 |
| Cuadrilla Resources Limited | Mining & quarrying | 2008 |
| Cuadrilla South Cleveland Limited | Mining & quarrying | 2016 |
| Cuadrilla Weald Limited | Mining & quarrying | 2009 |
| Cuadrilla Well Services Limited | Mining & quarrying | 2009 |
| Cuba Holdings Limited | Financial services | 2008 |
| Cuba Topco Limited | Financial services | 2022 |
| Cubanacho Ltd | Hospitality | 2020 |
| Cubay Ltd | Wholesale & retail | 2026 |
| Cube & Partners Limited | Other services | 2024 |
| Cube 8 Studio Limited | Professional & scientific | 2016 |
| Cube Academy (PK) Limited | Other services | 2024 |
| Cube Academy Limited | Education | 2016 |
| Cube Accountants Limited | Professional & scientific | 2015 |
| Cube Architecture and Design Limited | Professional & scientific | 2013 |
| Cube Careers Limited | Other services | 2019 |
| Cube Casting Ltd | Administrative & support | 2024 |
| Cube Connect Limited | Other services | 2024 |
| Cube Design Solutions Ltd | Professional & scientific | 2019 |
| Cube Distribution Service Ltd | Transport & logistics | 2020 |
| Cube for Contracting Ltd | Real estate | 2024 |
| Cube Group Marketing Limited | Administrative & support | 2017 |
| Cube Holdings Ltd | Extraterritorial | 2017 |
| Cube Homes Limited | Construction | 2007 |
| Cube Insolvency Limited | Other services | 2024 |
| Cube International Trading Co., Ltd | Wholesale & retail | 2020 |
| Cube Lofts & Extensions Limited | Construction | 2021 |
| Cube Taxation Limited | Professional & scientific | 2020 |
| Cube Travels Limited | Wholesale & retail | 2014 |
| Cube Ventilation Services Ltd | Construction | 2024 |
| Cubed Cuts Limited | Other services | 2020 |
| Cubes Contracting Limited | Construction | 2016 |
| Cubetails Ltd | Wholesale & retail | 2025 |
| Cubic Lifestyle Investments Ltd | Real estate | 2022 |
| Cubic Modular Systems U.K. Limited | Manufacturing | 1999 |
| Cubic Properties Ltd | Real estate | 2023 |
| Cubicle Enclosure Systems Limited | Manufacturing | 1989 |
| Cubixquality Ltd | Wholesale & retail | 2020 |
| Cuby Holdings Limited | Financial services | 2015 |
| Cucctv Manchester Ltd | Wholesale & retail | 2022 |
| Cucina Fresca Ltd | Hospitality | 2023 |
| Cucina Unique Limited | Construction | 2013 |
| Cuckoo Design Limited | Professional & scientific | 2008 |
| Cuckoo Property Ltd | Real estate | 2021 |
| Cuckoo Repairs Ltd | Wholesale & retail | 2021 |
| Cuco Coffee Limited | Administrative & support | 2024 |
| Cucul Ltd | Transport & logistics | 2022 |
| Cucumber Catering Limited | Hospitality | 2019 |