| CWT Walsall Limited | Hospitality | 2024 |
| CX Centric Limited | Professional & scientific | 2024 |
| CX Peking Chef Limited | Hospitality | 2016 |
| CXH Limited | Financial services | 2025 |
| CXP Official Ltd | Wholesale & retail | 2019 |
| CXQ Ltd | Administrative & support | 2024 |
| CY (Finance) Limited | Administrative & support | 1998 |
| CY 8 Trading Ltd | Hospitality | 2025 |
| CY Good Choice Limited | Hospitality | 2016 |
| CY Project Ltd | Extraterritorial | 2023 |
| Cy-Sec Awareness and Consultancy Ltd | Information & communication | 2021 |
| Cyan Bidco Limited | Financial services | 2014 |
| Cyan Properties Limited | Real estate | 2018 |
| Cybakt Limited | Information & communication | 2022 |
| Cyber City Studios Ltd | Manufacturing | 2025 |
| Cyber Clock Ltd | Administrative & support | 2020 |
| Cyber Cloud Services Ltd | Information & communication | 2018 |
| Cyber Conformity Ltd | Information & communication | 2018 |
| Cyber Furnishings Ltd | Wholesale & retail | 2025 |
| Cyber Origin Ltd | Information & communication | 2022 |
| Cyber Resilience Consulting Ltd | Information & communication | 2016 |
| Cyber Security Group Ltd | Information & communication | 2019 |
| Cyber Security Strategies Limited | Information & communication | 2017 |
| Cyber Software Limited | Information & communication | 2025 |
| Cyber Technology Solutions Ltd | Information & communication | 2017 |
| Cyber Tzar Limited | Information & communication | 2021 |
| Cyber Unit Ltd | Administrative & support | 2026 |
| Cyberbizz Techno Limited | Information & communication | 2020 |
| Cybercentrik Services Limited | Information & communication | 2023 |
| Cyberedge GTM Ltd | Information & communication | 2025 |
| Cyberix Solutions Ltd | Information & communication | 2021 |
| Cyberland Microsystems Ltd | Wholesale & retail | 2026 |
| Cybermed (U.K.) Limited | Manufacturing | 1973 |
| Cybernetix Computing Limited | Information & communication | 2002 |
| Cyberpsychologist Limited | Information & communication | 2012 |
| Cyberq Group Holdings Ltd | Financial services | 2023 |
| Cyberq Group Limited | Information & communication | 2016 |
| Cyberq Group Offshore Ltd | Information & communication | 2020 |
| Cyberseq Ltd | Information & communication | 2025 |
| Cybersimplix Solutions Ltd | Information & communication | 2026 |
| Cybersphere Solutions Limited | Information & communication | 2023 |
| Cybersure Consulting Limited | Information & communication | 2022 |
| Cyberukwise Limited | Wholesale & retail | 2023 |
| Cyberwrx Ltd | Information & communication | 2021 |
| Cybion Search Ltd | Professional & scientific | 2026 |
| Cyborgate Ltd | Wholesale & retail | 2024 |
| CYC (Birmingham) Limited | Real estate | 2003 |
| CYC Assets Limited | Real estate | 2023 |
| Cycl Limited | Water & waste | 2025 |
| Cycling History (Publishing) Ltd | Information & communication | 2010 |
| Cycling Sports Ltd | Wholesale & retail | 2013 |
| Cycloid Consultants Ltd | Other services | 2022 |
| Cyclone Media Ltd | Information & communication | 2005 |
| Cycoll Limited | Information & communication | 2013 |
| Cycorco Ltd | Transport & logistics | 2025 |
| Cyeilas Beauty Limited | Other services | 2025 |
| Cygiene Limited | Professional & scientific | 2026 |
| Cygnet (New Street) Limited | | 1992 |
| Cygnet Food Group Limited | Wholesale & retail | 2019 |
| Cygnet Foods Holdings Limited | Manufacturing | 2010 |
| Cygnet Foods Limited | Manufacturing | 1995 |
| Cygnet Housing Limited | Real estate | 2024 |
| Cygnet Insurance Services Limited | Financial services | 2019 |
| Cygnet Project Solutions Ltd | Information & communication | 2022 |
| Cygnet Properties Ltd | Construction | 2015 |
| Cygnet Property Management PLC | Real estate | 1991 |
| Cylaworg Ltd | Professional & scientific | 2023 |
| Cylosafe Limited | Manufacturing | 2024 |
| Cynefin Ltd | Hospitality | 2020 |
| Cynisterclothing Ltd | Wholesale & retail | 2024 |
| Cynosaj Services Ltd | Hospitality | 2022 |
| Cynosure Consulting Limited | Professional & scientific | 2023 |
| Cynq Limited | Information & communication | 2025 |
| Cynthia's (With the Good Hair) Ltd | Other services | 2016 |
| Cypal Limited | Information & communication | 2024 |
| Cyphercloud Limited | Information & communication | 2022 |
| Cypress Global HR Limited | Professional & scientific | 2023 |
| Cypress Innovations Limited | Professional & scientific | 2024 |
| Cyprus-British Chamber of Commerce and Industry | Administrative & support | 1993 |
| Cyrena Monique Ltd | Administrative & support | 2018 |
| Cyrus Transport Services Ltd | Transport & logistics | 2019 |
| Cysr Ltd | Administrative & support | 2022 |
| Cytometric Engineering Ltd | Manufacturing | 2014 |
| Cyza Ltd | Wholesale & retail | 2024 |
| CZ Floral Designs Ltd | Wholesale & retail | 2018 |
| Czech & Slovak Club UK C.I.C. | Education | 2013 |
| Czero Castle Eden Limited | Real estate | 2024 |
| Czero Devco Limited | Real estate | 2017 |
| Czero Developments Limited | Construction | 2008 |
| Czesiek Transport Limited | Transport & logistics | 2016 |
| CZN Birmingham Ltd | Hospitality | 2025 |
| CZR International Ltd | Construction | 2023 |
| Céless Ltd | Wholesale & retail | 2026 |
| D & a Catering Ltd | Hospitality | 2019 |
| D & a Gibbs Ltd | Real estate | 2023 |
| D & a Solicitors Limited | Professional & scientific | 2013 |
| D & B Catering Services (Midlands) Limited | Hospitality | 2009 |
| D & D Global Services Ltd | Health & social care | 2022 |
| D & D Nails Ltd | Other services | 2019 |
| D & D Real Estates Ltd | Real estate | 2019 |