| Brencon Ltd | Real estate | 2021 |
| Bretton Hall Solar Farm Ltd | Energy | 2025 |
| Brunswick Ironworks Limited | Manufacturing | 2006 |
| Bryn Celyn Road Management Company Limited | Hospitality | 2013 |
| Bryn Derwen (Waunfawr) Limited | Hospitality | 2023 |
| Bryn Hughes Limited | Administrative & support | 2025 |
| Brynrefail Chapel Management Company Limited | Households | 2019 |
| Brynteg Consulting Ltd | Professional & scientific | 2016 |
| Bubble DEN Limited | Wholesale & retail | 2023 |
| Bulbrook Properties Limited | Real estate | 2018 |
| BYD Bach CIC | Other services | 2024 |
| BYW Bywyd (Living Life) CYF. | Wholesale & retail | 2003 |
| Byw'N Iach CYF | Arts & recreation | 2018 |
| Bywyd Bywiog CYF | Health & social care | 2004 |
| C Garlick Plastering & Building Ltd | Construction | 2017 |
| C M Denham Ltd | Agriculture & fishing | 2016 |
| C&S Limitedd Ltd | Wholesale & retail | 2026 |
| C.G Marine Ltd | Manufacturing | 2023 |
| Caban CIC | Hospitality | 1999 |
| Caddyrent Limited | Administrative & support | 2015 |
| CAE Glas Developments Ltd | Construction | 2014 |
| CAE Haidd Bach Lets Ltd | Real estate | 2021 |
| CAE Main Livery Ltd | Agriculture & fishing | 2019 |
| CAE TY Capel Management Company Limited | Households | 2016 |
| Caer Service Station Caernarfon Ltd | Wholesale & retail | 2019 |
| Caer Service Station Ltd | Wholesale & retail | 2019 |
| Caerhos CYF | Professional & scientific | 2022 |
| Caernarfon Artist Regional Network Ltd | Other services | 2019 |
| Caernarfon Engineering Services Ltd | Manufacturing | 2021 |
| Caernarfon Kebab Ltd | Hospitality | 2016 |
| Caernarfon Masonic Hall Ltd | Information & communication | 2022 |
| Caernarfon-Apartments.Com Limited | Hospitality | 2018 |
| Caffi Betty’S Ltd | Hospitality | 2021 |
| Caillan Harris Ltd | Construction | 2023 |
| Calo Cars Ltd | Wholesale & retail | 2025 |
| Camera TWT Ltd | Information & communication | 2020 |
| Canllaw (Eryri) CYF | Health & social care | 1999 |
| Canol Y Coed Glamping Ltd | Hospitality | 2020 |
| Canolfan Y Fron | Hospitality | 2016 |
| Carmel Driving School & Travel Ltd | Transport & logistics | 2023 |
| Carreg Trefor CYF | Mining & quarrying | 2025 |
| Cars Gwynedd Limited | Wholesale & retail | 2026 |
| Castle Marine Limited | Manufacturing | 2005 |
| Castle Square Clinic Limited | Health & social care | 2013 |
| Castle View Caernarfon Limited | Hospitality | 2018 |
| CBM Technical Services Ltd | Professional & scientific | 2024 |
| Cefn DU Construction Limited | Construction | 2006 |
| Cegin Y Ddraig CYF. | Hospitality | 2023 |
| Ceirios Coffee Ltd | Hospitality | 2025 |
| Celta Maritime Ltd | Information & communication | 2026 |
| Celtic Arts and Crafts Limited | Wholesale & retail | 2021 |
| Celtic Computers (Wales) Ltd | Wholesale & retail | 2026 |
| Celtic Flooring & Restoration Ltd | Construction | 2021 |
| Celtic Heritage Construction and Stonemasonry Limited | Construction | 2015 |
| Celtic NW Group Ltd | Public administration | 2026 |
| Cemlyn Ltd | Construction | 2025 |
| Cerdd Angharad WYN Jones CYF. | Information & communication | 2018 |
| Cerrig Cynrig Farm Limited | Agriculture & fishing | 2000 |
| Ceunant Construction Ltd | Construction | 2025 |
| Charlton Oliver Properties Ltd | Real estate | 2024 |
| Churban Limited | Information & communication | 2014 |
| Cibyn MOT Centre Ltd | Wholesale & retail | 2009 |
| Cimera C.B.C | Arts & recreation | 2014 |
| Circoarts | Arts & recreation | 2018 |
| CK Cabs Ltd | Transport & logistics | 2017 |
| Ck-Ynys MON CYF | Transport & logistics | 2024 |
| Clarity Aquatics and Landscapes Ltd | Construction | 2018 |
| Clean Goat Co. Ltd | Manufacturing | 2025 |
| Cleanrus Limited | Construction | 2021 |
| Clen Construction Ltd | Construction | 2016 |
| Cliff Hughes Ltd | Information & communication | 2020 |
| Climb Snowdon Limited | Administrative & support | 2019 |
| Clinical Wheels DNM Ltd | Wholesale & retail | 2024 |
| Clogwyn Hydro Limited | Energy | 2014 |
| CLP Surfacing & Groundworks Ltd | Construction | 2026 |
| Clwb Golff Caernarfon CYF | Hospitality | 2023 |
| Clwb Plant Segontiwm CYF | Health & social care | 2008 |
| Clwb Rygbi Caernarfon Cyfyngedig | Arts & recreation | 2012 |
| Coastal Caravans North Wales Ltd | Wholesale & retail | 2022 |
| Code ARC Services Ltd | Construction | 2014 |
| Coed Madog CYF | Construction | 2024 |
| Coffi Cofi CYF | Hospitality | 2025 |
| Colin Jones Plastering Limited | Construction | 2016 |
| Colton & SON Utility Contractors Limited | Water & waste | 2018 |
| Colton Drainage Services Limited | Water & waste | 2015 |
| Colwydr CYF | Energy | 2018 |
| Complete Digital Design Solutions Limited | Information & communication | 2004 |
| Continuity Electrical Contractors Ltd | Construction | 2016 |
| Copa Coffi Limited | Manufacturing | 2025 |
| Corporate Data Management Limited | Professional & scientific | 2000 |
| Cosy Cottage Retreats Ltd | Hospitality | 2020 |
| Coupe-Evans Limited | Hospitality | 2025 |
| CPD Tref Caernarfon Town FC CYF | Arts & recreation | 2011 |
| Creative Consortium Solutions Limited | Information & communication | 2007 |
| Crochan Celf | Arts & recreation | 2004 |
| Cross Channel Entertainments Ltd | Arts & recreation | 2010 |
| Crown & Lilly Ltd | Hospitality | 2018 |
| Crusoe Digital Ltd | Information & communication | 2025 |
| CTD Social Care & Research Consultancy Limited | Health & social care | 2016 |
| Curtis Rentals Ltd | Real estate | 2017 |