| Cloudz Papers Ltd | Coatbridge | 2021 |
| Clough (Croydon) Limited | Barnsley | 1936 |
| Clough Ripley Ltd | Penzance | 2013 |
| Cloughbane Farm Foods Limited | Dungannon | 2012 |
| Cloughmor Consulting Ltd | Newry | 2018 |
| Clove Candle Company Limited | Ilminster | 2025 |
| Clove Coffee Limited | Dagenham | 2015 |
| Clove Origin Ltd | Birkenhead | 2026 |
| Clovelly Cloth Ltd | London | 2019 |
| Clover 51 Limited | Durham | 2012 |
| Clover Blue Ltd | Tamworth | 2026 |
| Clover Cabinet Makers Ltd | Weymouth | 2022 |
| Clover House Chocolate Ltd | London | 2021 |
| Clover Leaf Windows Limited | Stockton On Tees | 2006 |
| Clover Tool Europe Limited | Aberdeen | 2015 |
| Cloverbr Ltd | London | 2025 |
| Cloverbrook Limited | Burnley | 1979 |
| Cloverjay Limited | Framfield | 1993 |
| Cloverleif Limited | Liskeard | 2022 |
| Clovertone Limited | London. | 1975 |
| Clovertronix Ltd | Hornchurch | 2021 |
| Clovis Group Ltd | Edinburgh | 2016 |
| Clovis Lande Associates Limited | Tonbridge | 1988 |
| Clow Group Ltd. | | 1972 |
| Clow Life Limited | Stourbridge | 2021 |
| Clownfish Products Limited | Caterham | 2025 |
| CLP Air Group Limited | Wakefield | 1999 |
| CLP Fabrication Ltd | Hull | 2023 |
| CLP Trimmings Limited | Walsall | 2007 |
| Clprojectsuk Limited | Burnley | 2016 |
| CLR Dynamics Ltd | Coleford | 2023 |
| CLR Rooms Ltd | Hull | 2022 |
| CLS 2000 Limited | Hextable | 2000 |
| CLS Aviation Limited | Trelewis | 2008 |
| CLS Displays Ltd | Edenbridge | 2008 |
| CLS Facilities Limited | Hoo, Rochester | 2008 |
| CLS Identification Limited | Baildon | 2008 |
| CLS Interiors Ltd | London | 2023 |
| CLS Machining Ltd | Worksop | 2013 |
| CLS Wind Group Ltd | Edinburgh | 2025 |
| Cls-Steel Ltd | Bishop'S Stortford | 2019 |
| Clsb Ltd | Barnet | 2023 |
| Clsm Mechanical Engineering Limited | Milton Keynes | 2019 |
| Clthd Ltd | Leyton | 2023 |
| Club Brands Ltd | London | 2026 |
| Club Cana Ltd | London | 2018 |
| Club Cardonor Limited | Bromley | 2024 |
| Club Forty Four Limited | London | 2022 |
| Club FSG Limited | Waltham Cross | 2016 |
| Club KIT Print Ltd | East Kilbride | 2022 |
| Club Mania Limited | London | 2025 |
| Club Medals Limited | Belfast | 2024 |
| Club Mera Ltd | London | 2025 |
| Club Neuro Ltd | London | 2024 |
| Club Pottery Limited | Glasgow | 2023 |
| Club Rally Ltd | Reigate | 2025 |
| Club Salami Limited | Hitchin | 2026 |
| Club Screen Prints (Glasgow) Limited | Glasgow | 1977 |
| Club Scrunchies Ltd | Bromsgrove | 2021 |
| Club Seven Menswear Limited | London | 2021 |
| Club Sportswear Ltd | Wolverhampton | 2025 |
| Club Together Software 2022 Ltd | London | 2018 |
| Club Togs Limited | London | 2018 |
| Club Wolf Ltd | London | 2026 |
| CLUB1994 Ltd | London | 2025 |
| Clubb Concrete Ltd | Fareham | 2022 |
| Clubcaddy Golf Ltd | Barnsley | 2025 |
| Clubgrp Limited | Belfast | 2025 |
| Clubhouse Print Newcastle Limited | Newcastle Upon Tyne | 2025 |
| Clubkaddy Limited | Bristol | 2007 |
| Clubpro Ltd | Leyland | 2025 |
| Clubsports Midlands Ltd | Birmingham | 2019 |
| Clucas Diving & Marine Engineering Limited | East Yorkshire | 1998 |
| Clucas Method of Entry Limited | Cottingham | 1974 |
| Cluck Print Limited | London | 2016 |
| Clued Detection Limited | Feltham | 2025 |
| Cluequest Ltd | Uckfield | 2013 |
| Cluett Carpentry Ltd | Manchester | 2017 |
| Clukp Ltd | Greenford | 2021 |
| Clumber Products Ltd | Worksop | 2020 |
| Clumsy Hamster Limited | Bollington | 2024 |
| Cluny Fish Limited | | 2006 |
| Cluny Lace Company Limited | Derbyshire | 1975 |
| Cluson Engineering Limited | Petersfield | 1975 |
| Clustan Limited | Edinburgh | 1982 |
| Cluster Club Ltd | Blackburn | 2021 |
| Cluster Techs Ltd | London | 2024 |
| Clusterclean Limited | Telford | 2009 |
| Clustog CYF | Llandeilo | 2025 |
| Cluston Services Ltd | Smethwick | 2018 |
| Clutch & Flywheel Limited | Rossendale | 2007 |
| Clutch and Gearbox Ltd | Middlesbrough | 2025 |
| Clutchfix Limited | Wakefield | 2016 |
| Cluuo Group Ltd | Bristol | 2020 |
| CLW Plant & Commercial Ltd | Barnsley | 2026 |
| CLW Rail Limited | Cardiff | 2016 |
| Clwyd Compounders Limited | Wrexham | 1978 |
| Clwyd Concrete Co.Limited | Denbigh | 1954 |
| Clwyd Concrete Products Limited | Wrexham | 2010 |
| Clwyd Welding Services Limited | Exeter | 1983 |