| BT Mullen Ltd | Professional & scientific | 2016 |
| BT2 Apartments Limited | Hospitality | 2016 |
| Buddhafield Trading Limited | Hospitality | 1998 |
| Budget Designer Homeworks Ltd | Wholesale & retail | 2012 |
| Bufflehead Ltd | Information & communication | 2026 |
| Build Wisee Ltd | Construction | 2020 |
| Build-Ni Ltd | Construction | 2016 |
| Building Repairs at North Down Ltd | Construction | 2023 |
| Bumble & Goose Ltd | Manufacturing | 2021 |
| Business Education & Management Services Ltd | Administrative & support | 2009 |
| BWA Heating Solutions Ltd | Construction | 2023 |
| Bwgan Games Ltd | Information & communication | 2022 |
| Bwyd AM Byth CIC | Education | 2020 |
| Bwyd DA Bangor Limited | Education | 2023 |
| Bwyd MOR Limited | Agriculture & fishing | 2012 |
| Bysus Lewis-Y-Llan Cyfyngedig | Transport & logistics | 2003 |
| Bywyd Gwyllt Glaslyn Wildlife | Arts & recreation | 2012 |
| C & a Asbestos Removal Ltd | Water & waste | 2004 |
| C and C Contractors North Wales Ltd | Construction | 2016 |
| C L Jones (Holding) Company Limited | Professional & scientific | 2010 |
| C&Db Ltd | Hospitality | 2018 |
| C&R Interiors Limited | Construction | 2013 |
| C. L. Jones Ltd. | Wholesale & retail | 2000 |
| C.C.R.S. Investments Ltd | Transport & logistics | 2019 |
| C.C.R.S. Prestige Storage Ltd | Transport & logistics | 2019 |
| C.C.R.S. Recovery Ltd | Transport & logistics | 2012 |
| C.J. Monaghan & Co. Ltd | Wholesale & retail | 2009 |
| Caball Ltd | Construction | 2015 |
| Caban Y Faenol CYF | Health & social care | 2012 |
| Cabbage Patch Day Nursery Ltd. | Education | 2016 |
| Cadentia Technologies Limited | Information & communication | 2026 |
| Cadi Property's Ltd | Real estate | 2025 |
| Cadnant Group Ltd | Administrative & support | 2023 |
| Caelgair CYF | Administrative & support | 2012 |
| Caerhun Farm Ltd | Agriculture & fishing | 2020 |
| Caernarfon Container Hire Ltd | Administrative & support | 2024 |
| Cafe B Balloo Limited | Hospitality | 2019 |
| Cafe Trax Ltd | Hospitality | 2023 |
| Cafe UNO Limited | Hospitality | 2009 |
| Caffi 364 Ltd | Hospitality | 2021 |
| CAI Williams Roofing Services Ltd | Construction | 2025 |
| Cairn Bay Lodge Ltd | Hospitality | 2019 |
| Cairns Investment Holdings Ltd | Real estate | 2024 |
| Callacab Bangor Ltd | Transport & logistics | 2022 |
| Callacab Cars Ltd | Administrative & support | 2025 |
| CAM 2000 Limited | Professional & scientific | 1996 |
| Camerata Ireland | Arts & recreation | 1999 |
| CAMMY3DPRINTS Limited | Manufacturing | 2021 |
| Campbell Catering Limited | Hospitality | 2023 |
| Canny Tech Limited | Information & communication | 2017 |
| Cantley Construction Limited | Construction | 2005 |
| Capgap Limited | Real estate | 2014 |
| Caprice (Bangor) Limited | Wholesale & retail | 1983 |
| Captain Onion UK Limited | Information & communication | 2025 |
| Caramôn Cyfyngedig | Manufacturing | 2020 |
| Caravan Services North Wales Ltd | Wholesale & retail | 2022 |
| Carbreakdownservice Ltd | Transport & logistics | 2025 |
| Card Connect Ltd | Administrative & support | 2018 |
| Career Path E-Learning & HR Services Ltd | Administrative & support | 2025 |
| Carelink Homecare Services Limited | Health & social care | 2002 |
| Cargo Drive INS Ltd | Hospitality | 2020 |
| Carlton (North Wales) Limited | Real estate | 1943 |
| Carnhill (N.I.) Limited | Construction | 1989 |
| Carno Ltd | Hospitality | 2025 |
| Carnview Management Company Ltd | Extraterritorial | 2025 |
| Carreg Y Gath CYF | Hospitality | 2022 |
| Carren Developments Limited | Extraterritorial | 1983 |
| Carriage Mews Management Company Limited | Households | 1988 |
| Carrickfergus VETS4PETS Limited | Professional & scientific | 2010 |
| Carru Holdings Ltd | Real estate | 2023 |
| Carter Vincent LLP | | 2011 |
| Cascum Consultancy Limited | Professional & scientific | 2026 |
| Caseys Brows and Beauty Ltd | Other services | 2025 |
| Casgen Cyfyngedig | Hospitality | 2012 |
| Castell MON Limited | Manufacturing | 1977 |
| Castell Security Ltd | Administrative & support | 2025 |
| Castle Gate Apartments NO. 1 Limited | Extraterritorial | 2008 |
| Castle Lodge Apartments Limited | Extraterritorial | 1999 |
| Castle Property Investment Holdings Limited | Hospitality | 2016 |
| Castlemeghan Ltd. | Administrative & support | 2017 |
| Castom Civil Engineering Ltd | Construction | 2019 |
| Caulmert Limited | Water & waste | 2008 |
| CBA Media Limited | Information & communication | 2017 |
| Cbrett Mortgages Ltd | Financial services | 2026 |
| Cedarfield Developments Limited | Construction | 2007 |
| Cedarfield Management Company Limited | Real estate | 2016 |
| Cedrus One Limited | Financial services | 1994 |
| Cefn Coed Limited | Extraterritorial | 2024 |
| Cefnogi-Ogi CYF | Professional & scientific | 2024 |
| Cegin Productions Limited | Arts & recreation | 2005 |
| Ceir Hurio HÂF Bryn Jones CYF | Transport & logistics | 2022 |
| Celine Trading Ltd | Wholesale & retail | 2023 |
| Celsan CYF | Real estate | 2025 |
| Celtest Company Limited | Construction | 1980 |
| Celtonix Limited | Information & communication | 2023 |
| Cent Group Ltd | Real estate | 2024 |
| Central Avenue Management Company Limited | Extraterritorial | 2006 |
| Central Buildings One Ltd | Real estate | 2018 |
| Central Garage Bethesda Ltd | Wholesale & retail | 2019 |
| Ceramica ETC Ltd | Wholesale & retail | 2011 |