| Clovis Supplies Limited | Agriculture & fishing | 2025 |
| CLP Holdings Ltd | Real estate | 2017 |
| CLP Legal Limited | Professional & scientific | 2013 |
| Club Vision Ltd | Information & communication | 2025 |
| CLUB-104 Limited | Hospitality | 2026 |
| Clubcash Swindon Ltd | Arts & recreation | 2024 |
| Clyde Computers Southern Limited | Other services | 1997 |
| CM Building and Landscaping Ltd | Administrative & support | 2023 |
| CM COE Pottery Supplies Ltd | Manufacturing | 2025 |
| CM Contracting Ltd | Administrative & support | 2022 |
| CM Custom Accessories Limited | Manufacturing | 2025 |
| CM Deliveries Limited | Transport & logistics | 2024 |
| CM Facilities Ltd | Administrative & support | 2024 |
| CM Swindon Ltd | Health & social care | 2022 |
| CMB Destiny Ltd | Health & social care | 2022 |
| CMC Network Limited | Administrative & support | 2012 |
| CMD Motors Ltd | Manufacturing | 2024 |
| Cmgm Properties Limited | Real estate | 2023 |
| Cmmn Series Limited | Wholesale & retail | 2025 |
| Cmrm Retail Ltd | Wholesale & retail | 2025 |
| CMS Groundworks Limited | Construction | 2023 |
| Cmsrc Limited | Professional & scientific | 2016 |
| Cmyk People Limited | Information & communication | 2018 |
| Cmyk Rentals Limited | Real estate | 2023 |
| Co&Co Coaching and Consulting Ltd | Professional & scientific | 2024 |
| Coach House (Tewkesbury) Management Limited | Households | 2000 |
| Coach Masters Arena Ltd | Health & social care | 2025 |
| Coachwood Properties Ltd | Real estate | 2019 |
| Coalescence Ltd | Professional & scientific | 2014 |
| Coalfield Close Management Company Limited | Extraterritorial | 2025 |
| Coate Properties (Swindon) Limited | Real estate | 2025 |
| Coate Water Care (Arbory) Limited | Health & social care | 2007 |
| Coate Water Care Company (Church View Nursing Home) Limited | Health & social care | 2003 |
| Coate Water Care Company Limited | Health & social care | 2001 |
| Coate Water Developments Limited | Construction | 2025 |
| Coatstone Surfacing Limited | Construction | 2005 |
| Cobern Builders Limited | Construction | 2015 |
| Cobert Ltd | Hospitality | 2018 |
| Cobut Ltd | Manufacturing | 2022 |
| Coci Link Limited | Health & social care | 2016 |
| Cocoa Amour Ltd | Manufacturing | 2025 |
| Code Lloyd Ltd | Information & communication | 2020 |
| Code Pro QUO Ltd | Information & communication | 2023 |
| Coded Design Limited | Administrative & support | 2008 |
| Codefish Ltd | Information & communication | 2020 |
| Coder INK JET Printer Services Limited | Manufacturing | 1996 |
| Coderepo Ltd | Professional & scientific | 2023 |
| Codiun Limited | Wholesale & retail | 2013 |
| COE Capital Wealth Management Limited | Financial services | 2018 |
| Coepi Recruitment Limited | Administrative & support | 2017 |
| Cofal Solutions Ltd | Administrative & support | 2025 |
| Coffee BUD Limited | Manufacturing | 2017 |
| Coffee Crew Ltd | Hospitality | 2022 |
| Coffee Stop Brazil Limited | Hospitality | 2024 |
| Coffeebean Publishing Ltd | Information & communication | 2015 |
| Cofresh Limited | Wholesale & retail | 2025 |
| Cognisys Global Ltd | Hospitality | 2025 |
| Cognitive Team Ltd | Information & communication | 2018 |
| Cognivate Limited | Information & communication | 2018 |
| Cognix Ltd | Information & communication | 2024 |
| Coil Civil Engineering Ltd | Construction | 2019 |
| Colarezzz Ltd | Transport & logistics | 2025 |
| Colbrad Property Holdings Ltd | Real estate | 2022 |
| Colburn Commercial Ltd | Real estate | 2017 |
| Colburn Developments Limited | Construction | 1984 |
| Colburn East Limited | Construction | 2014 |
| Colburn Estates Ltd | Extraterritorial | 2013 |
| Colburn North Ltd | Construction | 2013 |
| Colburn Properties Limited | Real estate | 2023 |
| Cole Easdon Consultants Limited | Professional & scientific | 1986 |
| Colebrook Building Services Ltd | Construction | 2019 |
| Coles Scaffolding Contractors Ltd | Construction | 2013 |
| Coletto Group Ltd | Information & communication | 2025 |
| Coleview Trading Company Limited | Hospitality | 1991 |
| Colin Bentley Ltd | Hospitality | 2024 |
| Collaborative Care Services Ltd | Health & social care | 2020 |
| Collectors Hub Online Ltd | Wholesale & retail | 2025 |
| College Street Orthodontic Limited | Health & social care | 2010 |
| Collio Limited | Hospitality | 2019 |
| Collvett Limited | Wholesale & retail | 1982 |
| Colmes Limited | Real estate | 2024 |
| Coln Valley Renovations Limited | Construction | 2018 |
| Colonnade Conservatories Limited | Construction | 2000 |
| Coloursofweb.Com Limited | Information & communication | 2008 |
| Columbus Business Management Limited | Professional & scientific | 1997 |
| Coman Car Wash Ltd | Administrative & support | 2026 |
| Combined Construction Solutions Limited | Construction | 2020 |
| Combined IT Solutions Limited | Information & communication | 2009 |
| Combined Scaffolding Holdings Limited | Construction | 2023 |
| Combined Scaffolding Limited | Construction | 2000 |
| Comet Park Management Limited | Real estate | 1990 |
| Comex Construction Ltd | Construction | 2019 |
| Comfcare Services Ltd | Health & social care | 2014 |
| Comfrey House RTM Company Limited | Households | 2011 |
| Comil Consultants Ltd | Information & communication | 2007 |
| Comitia Holdings Limited | Financial services | 2026 |
| Comitia Technologies Limited | Information & communication | 2026 |
| Comitia UK Ltd | Information & communication | 2026 |
| Comm-Versation Ltd | Professional & scientific | 2025 |
| Commerce House (Swindon) Limited | Real estate | 2010 |