| CHP 39 Ltd | Administrative & support | 2019 |
| CHP Payments Ltd | Other services | 2019 |
| Chris Davies Holdings Ltd | Extraterritorial | 2024 |
| Chris Grey Fire Doors Limited | Construction | 2008 |
| Chris Harvey Tattoo Ltd | Other services | 2019 |
| Chris Jewell Limited | Administrative & support | 2003 |
| Chris Jones Surveying and Property Services Limited | Professional & scientific | 2016 |
| Chris O'Sullivan Properties Limited | Real estate | 2003 |
| Chriscor Ltd | Construction | 2014 |
| Chrisden Properties Limited | Real estate | 2026 |
| Chrisp Consulting Engineers Ltd | Professional & scientific | 2024 |
| Chrisper Limited | Wholesale & retail | 2025 |
| Christ Community Global Limited | Other services | 2025 |
| Christal Audio Visual Limited | Information & communication | 2012 |
| Christanhealy Ltd | Hospitality | 2025 |
| Christian Jones Financial Services Ltd | Financial services | 2011 |
| Christown Empire Limited | Manufacturing | 2026 |
| Chromenet Limited | Water & waste | 2004 |
| Chrys SW11 Limited | Information & communication | 2015 |
| Chrysalis HB Holdings Ltd | Financial services | 2024 |
| CHS Trading Ltd | Wholesale & retail | 2020 |
| Chunk Monkey Ltd | Manufacturing | 2024 |
| Chunks Munchbox Ltd | Hospitality | 2023 |
| Church Aesthetics Ltd | Health & social care | 2025 |
| Church House Farm Getaways Ltd | Hospitality | 2021 |
| Church Lane Antiques Limited | Wholesale & retail | 2006 |
| Churchill Wealth & Property Management Limited | Real estate | 2006 |
| Ciello Ltd | Information & communication | 2025 |
| Cigno Holdings Ltd | Financial services | 2019 |
| Cigno Ltd | Wholesale & retail | 2018 |
| Cigno Properties Ltd | Real estate | 2019 |
| Cilbenrick Limited | Financial services | 2004 |
| Cinar Umut Ltd | Wholesale & retail | 2017 |
| Cinch Digital Ltd | Professional & scientific | 2004 |
| Cincle Plongeur Limited | Real estate | 2013 |
| Cinema & Go Ltd | Hospitality | 2020 |
| Cinema&Co. Swansea Ltd | Wholesale & retail | 2019 |
| Ciorty Ltd | Transport & logistics | 2025 |
| Ciotek Limited | Professional & scientific | 2003 |
| Circus Eruption | Arts & recreation | 1996 |
| Citizens Advice Swansea Neath Port Talbot Limited | Other services | 1983 |
| Citrim Properties Limited | Real estate | 2006 |
| City Barbers (Swansea) Limited | Other services | 2018 |
| City Cafe (Swansea) Ltd | Hospitality | 2019 |
| City Centre Storage Limited | Administrative & support | 2025 |
| City Electro Limited | Extraterritorial | 1995 |
| City Grill & Pizza Ltd | Hospitality | 2026 |
| City Hire Gorseinon Limited | Administrative & support | 2006 |
| City Lighting Limited | Administrative & support | 2015 |
| City Meat &Fish Centre Ltd | Wholesale & retail | 2026 |
| City School of Languages Limited | Education | 2006 |
| City Shoes (Newport) Ltd | Wholesale & retail | 2004 |
| City Staycations Ltd | Real estate | 2025 |
| City Store Ltd | Wholesale & retail | 2024 |
| CITY81 Limited | Information & communication | 2008 |
| Cityflow Plumbing and Heating Limited | Construction | 2026 |
| Civic Motoring Services Limited | Wholesale & retail | 1992 |
| Civil Engineer Hendy Ltd | Professional & scientific | 2018 |
| CJ & AJ Butler Limited | Agriculture & fishing | 2016 |
| CJ Nautical LLP | | 2026 |
| CJ Property Developments (SW) Ltd | Real estate | 2024 |
| CJ3 Ltd | Construction | 2020 |
| CJC Courier Services Ltd | Transport & logistics | 2025 |
| CJG Contracting Ltd | Financial services | 2005 |
| CJI Properties (Pontarddulais) Limited | Households | 2014 |
| CJL Lighting Design Limited | Wholesale & retail | 2017 |
| Cjones Supplies Ltd | Wholesale & retail | 2022 |
| CJP IT Consultancy Limited | Information & communication | 2018 |
| CJP Testing Services Ltd | Wholesale & retail | 2019 |
| Cjpadpar Ltd | Professional & scientific | 2020 |
| CJS Notary Limited | Professional & scientific | 2021 |
| Cjwr Construction Ltd | Construction | 2024 |
| CK Llanelli RCS Limited | Hospitality | 2025 |
| CKF Transport Ltd | Transport & logistics | 2018 |
| Ckhouses Ltd | Real estate | 2016 |
| Ckma Consultancy Limited | Wholesale & retail | 2019 |
| CKS Fuels Ltd | Wholesale & retail | 2017 |
| CL Dental Implantology Ltd | Health & social care | 2024 |
| CL Thai Catering Limited | Hospitality | 2019 |
| Cladinox International Limited | Professional & scientific | 2025 |
| Claemore Building Contractor Limited | Construction | 2017 |
| Claim Solution Corp Limited | Financial services | 2022 |
| Claimrite Limited | Financial services | 2013 |
| Claimrite Partners LLP | | 2023 |
| Claims Connexion (UK) Limited | Financial services | 2002 |
| Claimwise (UK) Ltd | Administrative & support | 2025 |
| Claire AA Smith Psychology Ltd | Education | 2025 |
| Claire Ions Ltd | Administrative & support | 2023 |
| Claire Wallace (Hairdressing) Limited | Other services | 2002 |
| Clanfern Properties Ltd | Real estate | 2001 |
| Clarion Court Management Limited | Real estate | 1990 |
| Clarity DUE Diligence Limited | Administrative & support | 2023 |
| Clarity Holdings Limited | Administrative & support | 2015 |
| Clark Group Fabrications Ltd | Construction | 2016 |
| Claryzo Ltd | Wholesale & retail | 2025 |
| Clase Palace Kitchen Ltd | Hospitality | 2024 |
| Clase Supermarket Ltd | Wholesale & retail | 2015 |
| Classe 4 A'S Limited | Hospitality | 2018 |
| Classic CUT Barber Ltd | Other services | 2014 |
| Classic PVC Home Improvements Limited | Construction | 1994 |