| Cashmore Mortgages Ltd | Banbury | 2024 |
| Cashova FX Limited | London | 2025 |
| Cashpot Limited | London | 2010 |
| Cashsend Limited | Ellesmere Port | 2016 |
| Cashup Ltd | Cardiff | 2015 |
| Cashvia Limited | London | 2025 |
| Cashy Holdings Limited | London | 2022 |
| Casi.Kasi Limited | Manchester | 2018 |
| Casini Corp Limited | London | 2026 |
| Casini Holdings Limited | Southend-On-Sea | 2021 |
| Casino Holdings Limited | Strabane | 2016 |
| Casint Ltd | Reading | 2025 |
| Casita Holdings Limited | Weybridge | 2016 |
| Caskad Enterprises (PVT) Limited | | 1978 |
| Caskguard Limited | Milton Keynes | 2025 |
| Caskyn Holdings Limited | London | 2026 |
| Caslas Trading Co Ltd | Maidenhead | 2024 |
| Caslin Holdings Ltd | Eastbourne | 2019 |
| Caslpts Ltd | Preston | 1980 |
| Casmax Holdings Ltd | Newcastle Upon Tyne | 2023 |
| Casmax Ltd | Bury St Edmunds | 2023 |
| Casmon Investments Limited | Hemel Hempstead | 2026 |
| Caso Investments Limited | London | 2018 |
| Casoni Limited | Vines Cross | 2014 |
| Casp Holdings Limited | King'S Lynn | 2019 |
| Caspean Investments Ltd | London | 2017 |
| Casper Holdings Ltd | Clitheroe | 2020 |
| Casper Shipping Holdings Limited | Middlesbrough | 2014 |
| Casper Specialty Group Limited | London | 2022 |
| Casper Specialty UK Limited | London | 2022 |
| Casper UK Bidco Limited | London | 2014 |
| Caspercat Holdings Limited | Truro | 2021 |
| Caspian Assured Holdings Limited | Manchester | 2024 |
| Caspian Assured Ltd | Manchester | 2009 |
| Caspian Capital Limited | London | 2012 |
| Caspian Capital Management Ltd | Eastbourne | 2025 |
| Caspian Childcare Group Ltd | Chippenham | 2026 |
| Caspian Enterprises Limited | London | 2021 |
| Caspian Group of Companies Ltd | London | 2024 |
| Caspian Holdings (U.K) Limited | Wimborne | 2017 |
| Caspian Holdings (UK) Ltd | Ilford | 2024 |
| Caspian Limited | London | 2025 |
| Caspian One Group Limited | Bournemouth | 2025 |
| Caspian Partners Limited | London | 2023 |
| Caspian Properties Limited | London | 2004 |
| Cass & BAM Limited | Elland | 2024 |
| Cass Group Holdings Limited | Coventry | 2019 |
| Cass UK Capital Ltd | Bolton | 2016 |
| Cass-Stephens Insurances Limited | Gloucester | 1967 |
| Cass-Stephens Life & Pensions Limited | Gloucester | 2019 |
| Cassandra Holdings Ltd | London | 2023 |
| Cassandra's Prophecies Limited | London | 2026 |
| Cassar Holdings Limited | Weybridge | 2023 |
| Cassel Investments Limited | York | 2019 |
| Cassell Holdings Ltd | Nottingham | 2024 |
| Cassette Holdings Ltd | Cannock | 2024 |
| Cassey Grove Holdings Limited | Oldham | 2023 |
| Cassian Capital (UK) Limited | London | 2002 |
| Cassidy Group Propco 1 Ltd | Leamington Spa | 2022 |
| Cassidy Group Propco 2 Ltd | Leamington Spa | 2022 |
| Cassio Finance Limited | Watford | 2025 |
| Cassiobury Consultants Limited | Hertfordshire | 1979 |
| Cassiopeia 1958 Holdings Limited | Leeds | 2022 |
| Cassiopeia Group Ltd | Calne | 2025 |
| Cassiopeia Star Finance Limited | Southampton | 2017 |
| Cassiopeia Star Holdings Limited | Southampton | 2017 |
| Cassiopeia Star Investments Limited | Southampton | 2020 |
| Cassius Clay Limited | Croydon | 2022 |
| Cassius Holdco Ltd | Watford | 2025 |
| Cassius Holdings (Sussex) Ltd | Chichester | 2024 |
| Cassius Holdings Ltd | Southwark | 2022 |
| Cassius Investments Limited | London | 2017 |
| Casslink Ltd | London | 2026 |
| Casson Investments Limited | Preston | 2024 |
| Cassons Financial Planning Limited | Altrincham | 2012 |
| Cast & Crew Entertainment Services, Ltd. | Bromsgrove | 2019 |
| Cast Group Holdings Ltd | Manchester | 2025 |
| Cast Group Services Ltd | Brentwood | 2021 |
| Cast Holdco Limited | Sevenoaks | 2025 |
| Cast Holdings Limited | Norwich | 2015 |
| Cast in Style Holdings Limited | Shifnal | 2023 |
| Cast Iron Security Ltd | Hessle | 2020 |
| Cast Iron Services Ltd | York | 2022 |
| Cast Ward Holdings Ltd | Wellingborough | 2023 |
| Castal Limited | London | 2020 |
| Castaldo's Ltd | Newport | 2014 |
| Castamere Property Group Ltd | London | 2023 |
| Castanean (Holdings) Ltd | Hexham | 2020 |
| Castano Holdings Ltd | London | 2026 |
| Castara Investments Limited | London | 2019 |
| Castara Limited | Bury St Edmunds | 2021 |
| Castara Resources Limited | Bristol | 2013 |
| Castbless Estates Holdco Limited | Manchester | 2025 |
| Castel RE Ltd | London | 2018 |
| Castelan Group Limited | Weston Super Mare | 2015 |
| Castelan Limited | Weston Super Mare | 2011 |
| Castelina & Co. Ltd | London | 2018 |
| Castell 2021-1 Holdings Limited | London | 2021 |
| Castell 2021-1 PLC | London | 2021 |
| Castell 2022-1 Holdings Limited | London | 2022 |