| Colleen Allen Ltd | Agriculture & fishing | 2021 |
| Colossal Crash Wheelchair Rugby Ltd | Arts & recreation | 2023 |
| Colourblue Limited | Information & communication | 2006 |
| Commercial Operator Training Solutions Ltd | Education | 2009 |
| Community Hall Association of Seven Sisters | Arts & recreation | 2005 |
| Compound TC Ltd | Arts & recreation | 2025 |
| Concept Media Walls Limited | Manufacturing | 2025 |
| Concrete Structures & Floors Ltd | Construction | 2012 |
| Conrad Pipeline Services Limited | Construction | 2008 |
| Considerate Financial Limited | Financial services | 2015 |
| Construction Group Ltd | Construction | 2016 |
| Continental Equity Limited | Real estate | 2014 |
| Conveyor Machinery Supplies Limited | Manufacturing | 2020 |
| Cool-Link Limited | Construction | 2021 |
| Core Seal Limited | Construction | 2017 |
| Coregenichse Ltd | Professional & scientific | 2021 |
| Court's GAS Ltd | Construction | 2019 |
| Cover Stone Ltd | Wholesale & retail | 2021 |
| CPM21 Ltd | Professional & scientific | 2012 |
| Craft TY Property Ltd | Real estate | 2023 |
| Creative Paving (TVS) Ltd | Construction | 2022 |
| Creatorlens Limited | Information & communication | 2026 |
| Cremee Co Limited | Wholesale & retail | 2025 |
| Creunant Playgroup CIC | Health & social care | 2026 |
| Crofts Transport Limited | Transport & logistics | 2025 |
| Cronicl CYF | Information & communication | 2025 |
| Crossbeam Carpentry Ltd | Manufacturing | 2025 |
| Crouch Consultancy Ltd | Professional & scientific | 2026 |
| Crown Car Sales Limited | Wholesale & retail | 2020 |
| Crown Property & Roofing Specialist Ltd | Construction | 2024 |
| Crwth Ltd | Arts & recreation | 2006 |
| Crynant Home Improvements & Conservatories Ltd | Construction | 2018 |
| Crynant Plant and Construction Ltd | Construction | 2003 |
| Crynant Plant Limited | Construction | 1986 |
| Crynant Plant Sales Ltd | Administrative & support | 2018 |
| Crynant RFC Limited | Arts & recreation | 2018 |
| Crynant Skips and Recycling Ltd | Water & waste | 2003 |
| CS Animal Hydro & Physiotherapy Limited | Professional & scientific | 2014 |
| CS Veterinary Imaging Ltd | Professional & scientific | 2022 |
| Cuan O'Shea | Professional & scientific | 2008 |
| Cultive Limited | Other services | 2025 |
| Curry Bites Ltd | Hospitality | 2016 |
| Custom Industries Ltd | Manufacturing | 2015 |
| CW Project Developments Limited | Construction | 2002 |
| CWJ Properties & Lettings Ltd | Real estate | 2023 |
| CWM Upholstery Limited | Manufacturing | 2013 |
| Cwmbach Lodges Ltd | Hospitality | 2026 |
| Cwrt Construction Ltd | Construction | 2024 |
| Cwrt Herbert Colts CIC | Arts & recreation | 2026 |
| Cycling Podcast Productions Limited | Information & communication | 2019 |
| Cymru Connect Limited | Administrative & support | 2017 |
| Cynnal Group Limited | Professional & scientific | 2025 |
| Cyris Plant Operations Ltd | Construction | 2023 |
| Cyris Property Agents Limited | Real estate | 2024 |
| Cyris Property Management Ltd | Real estate | 2023 |
| Cysgod Properties Ltd | Real estate | 2025 |
| Cyvrix Limited | Transport & logistics | 2024 |
| D & a Properties Swansea Ltd | Real estate | 2026 |
| D & B Electrical Consultancy Ltd | Professional & scientific | 2026 |
| D & B Jones Properties Ltd | Real estate | 2024 |
| D a & C M Rowe Limited | Professional & scientific | 2010 |
| D Davies Consultancy Ltd | Administrative & support | 2022 |
| D John Carpentry and Building Contractors Ltd | Administrative & support | 2009 |
| D R Chemicals Limited | Manufacturing | 1975 |
| D&A Properties(Neath) Ltd | Real estate | 2023 |
| D&F Safe and Secure Roofing Limited | Construction | 2026 |
| D&H Commercial Motors Ltd | Wholesale & retail | 2022 |
| D&J Global Investments Ltd | Real estate | 2023 |
| D&S Lesuire Ltd | Hospitality | 2020 |
| D. J. Commercial Services Limited | Construction | 2017 |
| D.East Holdings Limited | Financial services | 2025 |
| D.J. Hitchman & SON Limited | Manufacturing | 2015 |
| D.R.F Waste Removals Limited | Water & waste | 2025 |
| Daffodil IT & Print Limited | Administrative & support | 2024 |
| Daisy's Boutique Ltd | Wholesale & retail | 2018 |
| Daks Inspection Limited | Professional & scientific | 2007 |
| Dala Catering Limited | Hospitality | 2026 |
| Daleys Developments Ltd | Construction | 2021 |
| Dancool Ltd | Manufacturing | 2022 |
| Daniel Perrin & Co Limited | Professional & scientific | 2016 |
| Daniel Wells Snooker Ltd | Arts & recreation | 2012 |
| Dansa Ltd | Administrative & support | 2008 |
| Daphneholdings Limited | Real estate | 2025 |
| Darkened Rooms Ltd | Information & communication | 2008 |
| Dartec Environmental Services Limited | Water & waste | 1990 |
| Darthvark Properties Ltd | Real estate | 2025 |
| Daters Elite Ltd | Other services | 2020 |
| Davad Ltd | Manufacturing | 2019 |
| Davans Property Ltd | Real estate | 2025 |
| David Fisher Electrical Ltd | Construction | 2026 |
| Davies MS Ltd | Real estate | 2024 |
| Davies-John Properties Limited | Real estate | 2026 |
| Dawl Diet Company Ltd | Other services | 2022 |
| Dazza's Ice Cream Limited | Hospitality | 2024 |
| Db's Roofing & Guttering Ltd | Construction | 2024 |
| DDE10 Promotions Limited | Arts & recreation | 2026 |
| Ddmn Properties Ltd | Real estate | 2023 |
| Dead Cert Electrical Ltd | Construction | 2023 |
| Debra Hughes Financial Consultancy Limited | Professional & scientific | 2015 |
| Deceitful Pictures Ltd | Information & communication | 2023 |