| Clan Ceramics Ltd | Market Harborough | 2007 |
| Clan Fit Edinburgh Ltd | Edinburgh | 2022 |
| Clan Royal of Scotland Limited | Carlisle | 1955 |
| Clan Structures Limited | Northallerton | 2011 |
| Clan Tartan Centre Limited | Dumfriesshire | 1977 |
| Clanbrassil Management Ltd | Ballyclare | 1998 |
| Clanchatton Birmingham Limited | Birmingham | 1998 |
| Clanco Floors and Ceilings Ltd | Inverness | 2011 |
| Clancy Investments Limited | Harefield, Uxbridge | 1954 |
| Clandon Park Limited | Market Harborough | 2016 |
| Clandon Wood Limited | Guildford | 2007 |
| Clanhem Developments Ltd | London | 2017 |
| Clanmack Limited | Northwich | 2021 |
| Clapham Investment & Mortgage Co.Limited | London | 1957 |
| Clara Luiza Hammond-Seaman Ltd | East Grinstead | 2022 |
| Clarabelle Care Services Limited | Norwich | 2022 |
| Clarajdn Ltd | London | 2026 |
| Clarandanbia Ltd | Norwich | 2017 |
| Clare Community Company Ltd | Leicester | 2025 |
| Clare Connery Enterprises Limited | 19 Alfred Street | 1984 |
| Clare Hambro & Co. Ltd | Evesham | 1998 |
| Clare Homes Limited | Cobham | 1991 |
| Clare House Management Company (Tottenham) Limited | London | 2004 |
| Clare Kerr Ltd. | Edinburgh | 2002 |
| Clare Kozakiewicz Mendonca Ltd | Thornton | 2017 |
| Clare Louise Dawkins Ltd | Burton | 2024 |
| Clare Veterinary Practice Limited | Belfast | 2011 |
| Clare's Gourmet Kitchen Ltd | Menai Bridge | 2017 |
| Claredale Finance Limited | Southampton | 1981 |
| Claregrange Care Homes Limited | Nottingham | 2004 |
| Claregrange Property Services Limited | Nottingham | 2004 |
| Claremont Road Management Company Limited | Middlesex | 2002 |
| Claremorris Consultancy Ltd | Solihull | 2022 |
| Clarence Events Ltd | St. Albans | 2019 |
| Clarence News (UK) Ltd | Birmingham | 2016 |
| Clarence Park Consultants Ltd | Marlow | 2024 |
| Clarence Road Properties Limited | Fleet | 2013 |
| Clarendon (28) Limited | London | 1997 |
| Clarendon Court (Wessex) Limited | Bournemouth | 2015 |
| Clarendon Feeds Limited | | 1996 |
| Clarendon Fine Art Limited | Lichfield | 2012 |
| Clarendon Mews (Worthing) Management Company Limited | Shoreham By Sea | 2007 |
| Clarendon Silos Limited | Belfast | 1997 |
| Clarendons Group Limited | Croydon | 2017 |
| Claret & CRU Ltd | Macclesfield | 2011 |
| Claret Services Ltd | | 2007 |
| Clareti Technologies Limited | London | 1986 |
| Clarges Rise Ltd | Preston | 2006 |
| Claridge Holdings Ltd | Kettering | 2023 |
| Claridge Inc Limited | Leicester | 2014 |
| Clarification Time Ltd | Norwich | 2021 |
| Clarion Cars Limited | Worthing | 1982 |
| Clarionix Ltd | London | 2026 |
| Claris' Kitchen Limited | Manchester | 2012 |
| Claritas Asset Management Limited | Quedgeley Gloucester | 1980 |
| Claritas Audio Visual Limited | Tamworth | 2015 |
| Claritas Consulting Ltd | Shrewsbury | 2012 |
| Claritas Limited | Wetherby | 2024 |
| Claritax Limited | Cheshire | 2003 |
| Clarity (EM) Limited | Cambridge | 2014 |
| Clarity Accountancy Services Ltd | Dundee | 2011 |
| Clarity Coaching Academy Limited | Oldham | 2016 |
| Clarity Compliance Ltd | London | 2024 |
| Clarity Concern Ltd | London | 2012 |
| Clarity Networks Ltd | Manchester | 2022 |
| Clarity News Limited | Walsall | 2025 |
| Clarity of Thought Marketing Limited | Sale | 2016 |
| Clarity Probate Limited | Lancing | 2005 |
| Clarity Property Group Ltd | Barnet | 2025 |
| Clarity Technology Holdings Limited | Milton Keynes | 2003 |
| Clarity Vision Limited | Daventry | 2013 |
| Clark and Company (Accountancy) Limited | Tonbridge | 2009 |
| Clark and Harvey Limited | Smethwick | 2015 |
| Clark Ceilings Ltd | Brighton | 2015 |
| Clark Contracts (Scotland) Ltd | Paisley | 2018 |
| Clark Digital Ltd | Sunderland | 2022 |
| Clark Eriksson Associates Limited | Falkirk | 1990 |
| Clark Investment Management Ltd | Liverpool | 2013 |
| Clark Mcleod Partnership Limited | Glasgow | 2022 |
| Clark Property Developments Limited | Bishop Auckland | 2016 |
| Clark's Holdings Limited | Cardiff | 2015 |
| Clark's Original Pies Limited | Cardiff | 2015 |
| Clarkbeck Law Limited | Wilmslow | 2019 |
| Clarke & Co Hockey Clinics Limited | Nottingham | 2023 |
| Clarke and Pulman (Burscough) Limited | Ormskirk | 2017 |
| Clarke and SON Builders Limited | Colchester | 2012 |
| Clarke EV Ltd | Leeds | 2020 |
| Clarke JCB Limited | Ormskirk | 2022 |
| Clarke Trustees NO. 1 Limited | Winchester | 2010 |
| Clarke Trustees NO. 2 Limited | Winchester | 2010 |
| Clarks & Sparks Ltd | Shipston-On-Stour | 2023 |
| Clarkson (Trustees) Limited | London | 1975 |
| Clarkson Air CON Services Limited | Northallerton | 2024 |
| Clarkson DRY Cargo Limited | London | 1997 |
| Clarkson Electrical Limited | Hull | 2018 |
| Clarkson Hammond and MAY Ltd | Hendre | 2013 |
| Clarkson Holdings Limited | London | 1997 |
| Clarkson Osborn International Limited | Nuneaton | 2001 |
| Clarkson Shipbrokers Limited | London | 1997 |
| Clarkson Tankers Limited | London | 1997 |