| Carbon Crown Ltd | Basildon | 2016 |
| Carbon Crusaders Limited | Llanelli | 2024 |
| Carbon Customs Ltd | Maidstone | 2020 |
| Carbon CUT Holdings Limited | Blandford Forum | 2016 |
| Carbon CUT UK Limited | Blandford Forum | 2011 |
| Carbon CUT UK Trading Ltd. | Blandford Forum | 2016 |
| Carbon Dog Ltd | Horncastle | 2025 |
| Carbon Dream Ltd | Luton | 2026 |
| Carbon Electra Ltd | Telford | 2021 |
| Carbon Equipment Limited | Wigan | 2014 |
| Carbon Europe Ltd | Milton Keynes | 2018 |
| Carbon Fabrications (Leicester) Limited | Leicester | 2009 |
| Carbon Fibre Profiles Ltd | London | 2014 |
| Carbon Fibre Tubes Limited | Denmead | 2003 |
| Carbon Filter Company Limited | Chester Le Street | 2011 |
| Carbon First Ltd | Newry | 2018 |
| Carbon Footprint College Limited | London | 2025 |
| Carbon Free Solutions Limited | Bromley | 2019 |
| Carbon Fresh Limited | London | 2016 |
| Carbon Gold Limited | Bristol | 2007 |
| Carbon Innovation Technology Ltd | Brighouse | 2008 |
| Carbon International Limited | Sheffield | 1991 |
| Carbon Kings Limited | London | 2019 |
| Carbon Klasse Ltd | Birmingham | 2023 |
| Carbon Light Forms Ltd | Blackpool | 2015 |
| Carbon Lighting Limited | Glasgow | 2007 |
| Carbon Mineralization Limited | Larne | 2024 |
| Carbon Mounts Ltd | Dumbarton | 2015 |
| Carbon Neutral Salvage Solutions Limited | Ormskirk | 2024 |
| Carbon Numbers Limited | Colchester | 2012 |
| Carbon OIL Renewables Ltd | Worksop | 2024 |
| Carbon Peak Limited | London | 2025 |
| Carbon Performance Ltd | Romford | 2026 |
| Carbon Plumbing Limited | Edinburgh | 2014 |
| Carbon Print Management Solutions Limited | Carterton | 2002 |
| Carbon Race Composites Ltd | Cambridge | 2026 |
| Carbon Reduction Technology Ltd | Leeds | 2008 |
| Carbon Reign Ltd | Bradford | 2025 |
| Carbon Repair UK Ltd | Brackley | 2014 |
| Carbon Ridge Ltd | London | 2025 |
| Carbon Shrink Limited | London | 2025 |
| Carbon Technology Limited | Sandbach | 1997 |
| Carbon Threesixty Limited | Chippenham | 2017 |
| Carbon Two Technologies Limited | London | 2023 |
| Carbon Upcycling Technologies UK Ltd | Leicester | 2021 |
| Carbon Wasp Ltd | Leeds | 2015 |
| Carbon Wolf Tactical Limited | London | 2024 |
| Carbon Woodcraft Limited | Leamington Spa | 2022 |
| Carbon Works Ltd | Cambridge | 2024 |
| Carbon Zero Industries Ltd | Gorebridge | 2020 |
| Carbon Zero Products Limited | Moneymore | 2024 |
| Carbon-K Ltd | London | 2019 |
| CARBON1000 Ltd | Bognor Regis | 2023 |
| CARBON30 Ltd | London | 2024 |
| CARBON350 Solutions Ltd | Petersfield | 2025 |
| CARBON75 Ltd | Cambridge | 2023 |
| CARBON8LIGHTING Ltd | Basingstoke | 2024 |
| Carbonaero Ltd | Sherborne | 2015 |
| Carbonara Limited | Banbury | 2022 |
| Carbonart Ltd | Wimborne | 2016 |
| Carbonation Techniques Limited | Altrincham | 2004 |
| Carboncutuk Ltd | Abingdon | 2023 |
| Carboned OUT Ltd | Bury St. Edmunds | 2024 |
| Carbonedge Studio Ltd | Portsmouth | 2026 |
| Carbonetic Watch Design Limited | London | 2024 |
| Carbonfoam Engine Solutions Ltd | Essex | 2025 |
| Carbonfront Limited | Mansfield | 2010 |
| Carbonish Structures Ltd | Plymouth | 2017 |
| Carbonistix Limited | Thornaby | 2024 |
| Carbonizer (Composites Racing) Ltd | Cambridge | 2026 |
| Carbonlite Converting Equipment Limited | Littleborough | 1979 |
| Carbonmakers Limited | Newport | 2019 |
| Carbonmeta Research Ltd | Hornchurch | 2021 |
| Carbonmineralisation Limited | Larne | 2025 |
| Carbonnano Ltd. | Felixstowe | 2015 |
| Carbonomics Limited | London | 1999 |
| Carbonowl Ltd | Leeds | 2020 |
| Carbontechnologi Ltd | Cambridge | 2026 |
| Carbonxilo Limited | Taunton | 2023 |
| Carbonyx Ltd | Manchester | 2025 |
| Carbotech-Europe Limited | Penrith | 2000 |
| Carbro Sheet Metal Co Limited | Stockport | 1999 |
| Carbrosah Ltd | Salisbury | 1994 |
| Carbtuneshop Ltd | Belfast | 2026 |
| Carcare (Wilpshire) Limited | Blackburn | 2006 |
| Carchem Ltd | York | 2010 |
| Carcinex Biopharma Ltd | Glasgow Central | 2025 |
| Carclo Diagnostic Solutions Limited | Mitcham | 2011 |
| Carclo PLC | Mitcham | 1924 |
| Carclo Technical Plastics Limited | Mitcham | 1995 |
| Carcode Limited | Mildenhall | 2020 |
| Carcoon Storage Systems (International) Limited | Derbyshire | 1994 |
| Carcoon Worldwide Workstations Limited | Derbyshire | 1994 |
| Carcraft Bodyshop Limited | Denby | 2019 |
| Carcroft Joinery Limited | Doncaster | 2001 |
| Card Compact Ltd. | London | 2011 |
| Card Couture Ltd | Swindon | 2015 |
| Card Gully Ltd | Wisbech | 2026 |
| Card Personalisation Solutions Limited | Market Rasen | 2003 |
| Card Printing Services Limited | Wolverhampton | 2004 |