| Cascelloid Limited | Manchester | 2003 |
| Cascenyx Limited | Ellesmere Port | 2026 |
| Casco Philatelic Services Limited | Folkestone | 2017 |
| Casdrove Limited | Stanstead Abbotts | 1977 |
| Case Managed Limited | Sevenoaks | 2025 |
| Casec UK Ltd | London | 2018 |
| Casecaviar Ltd | London | 2015 |
| Casedeal Limited | Bradford | 2025 |
| Casely-Hayford Limited | London | 2020 |
| Casewira Limited | Wellingborough | 2017 |
| Casey & Co. Bedrooms Ltd | Colchester | 2025 |
| Casey Jasey Ltd | Luton | 2021 |
| Casey Technology Limited | Rochdale | 2011 |
| Cash Converters Limited | York | 1992 |
| Cash in Hand Limited | Leigh On Sea | 2013 |
| Cash Kangaroo Limited | Solihull | 2013 |
| Cash Mart Ltd | Grays | 2013 |
| Cash Providers U.K. Limited | Telford | 2002 |
| Cash Vault Ltd | Harrogate | 2026 |
| CASH4CARS Leeds Limited | Leeds | 2014 |
| Cashasap.Co.Uk Limited | London | 2012 |
| Cashel Quarries Limited | Belfast | 2008 |
| Cashflow Direct Limited | Ormskirk | 2018 |
| Cashflow for Life Ltd | Witney | 2013 |
| Cashflow Invest Limited | London | 2021 |
| Cashflow Trading Limited | London | 2021 |
| Cashforcarsni.Com Ltd | Co Antrim | 2009 |
| Cashfriday Limited | Banbury | 1990 |
| Cashmere Moon Ltd | Maldon | 2022 |
| Cashmolane Ltd | Bradford | 1975 |
| Cashmore General Steels Limited | Edinburgh | 1935 |
| Casi Consulting Limited | Dunstable | 2025 |
| Casic Maler Limited | London | 2023 |
| Casino City Limited | Ipswich | 2008 |
| Casino Sites Ltd | London | 2016 |
| Casinolife Limited | London | 2010 |
| Casinos (UK) Ltd | Dartford | 2005 |
| Casius Limited | Halifax | 1998 |
| Cask Quest Limited | Sheerness | 2015 |
| Caskflasks Limited | Northumberland | 2002 |
| Casl EOT Limited | Chesterfield | 2021 |
| Casper Customs Limited | Middlesbrough | 2019 |
| Casper Holdings RG Ltd | Bracknell | 2022 |
| Casper Port Agency Limited | Middlesbrough | 2016 |
| Casperschopa Ltd | Bristol | 2022 |
| Caspian Data Limited | Swansea | 2008 |
| Caspian Pegasus Ltd | Manchester | 2017 |
| Caspian World Group Ltd | London | 2022 |
| Caspian Yachting Ltd | London | 2025 |
| Casquets Airlines Ltd | Bristol | 2014 |
| Cass Properties Services Limited | Dagenham | 2024 |
| Cass Stephens Commercial Limited | Gloucester, | 2006 |
| Cassette Ltd | Liverpool | 2022 |
| Casseys Property Ltd | Huddersfield | 2025 |
| CASSIE1967 Limited | Alfreton | 2013 |
| Cassini Asset Management Limited | Manchester | 2011 |
| Cassio Home Care Limited | Watford | 2022 |
| Cassiobury Homes Limited | Nicholson Road Torquay | 1966 |
| Cassiopea Limited | London | 2000 |
| Cassius Ltd | Cheltenham | 2009 |
| Cassnia Ltd | Kington | 2026 |
| Cassole Infrastructure Ltd | London | 2021 |
| Casson Beckman Business and Tax Advisers Limited | Walsall | 2004 |
| Casson's the English Herb Company Limited | Tadley | 2010 |
| Cassonbeckman.Co.Uk Limited | Hook | 2003 |
| Cassowary Consulting Limited | London | 2020 |
| Casstyle Blinds Limited | Sevenoaks | 1998 |
| Cast Agencies Europe Limited | Luton | 1983 |
| Cast Developments Limited | Sevenoaks | 2022 |
| Cast Iron Repair Services Limited | Coalville | 1996 |
| Castaldi Illuminazione (UK) Limited | Bordon | 2003 |
| Castalia Holdings Limited | Newport | 2007 |
| Castaway Consultants Ltd | Little Paxton St Neots | 2016 |
| Castedge Limited | Bridgend | 2025 |
| Castel Salbek Limited | Horsham | 2016 |
| Castelan Furniture Care Limited | Taunton | 2011 |
| Castelan Premier Care Limited | Taunton | 2011 |
| Castelan Services Limited | Weston Super Mare | 2015 |
| Castell & SON (Oxford) Limited | Oxford | 1947 |
| Castell Estates Limited | London | 2007 |
| Castellum Ltd | London | 2016 |
| Casthart Limited | Bridgend | 2026 |
| Castilian Way Ltd | Fareham | 2021 |
| Castillo DE Canena Olive Juice UK Ltd | London | 2022 |
| Castin ENT Limited | London | 2023 |
| Castle Air Group Limited | Liskeard | 1992 |
| Castle Bank Consulting Ltd | Chipping Norton | 2013 |
| Castle Belmont Limited | Folkestone | 2002 |
| Castle Cards Limited | Bradford | 1950 |
| Castle Care Products Ltd. | Hemel Hempstead | 2011 |
| Castle Care Villages Limited | Windsor | 2014 |
| Castle Close Residents Association Limited | Dover | 1995 |
| Castle Clyde Limited | Ayr | 2020 |
| Castle Combe Rally School Limited | Bristol | 2000 |
| Castle Comfort Centre Ltd | Newcastle | 2018 |
| Castle Court (Tandragee) Limited | Belfast | 2006 |
| Castle Court Funeral & Limousine Services Limited | Sutton Coldfield | 1945 |
| Castle Court Putney Wharf Limited | Cobham | 2002 |
| Castle Drive Management Company Limited | Horley | 1996 |
| Castle Electronic Technology Holdings Limited | Newcastle Upon Tyne | 2012 |