| C.V. LEE Consulting Ltd | Professional & scientific | 2018 |
| C.W.K. Systems Limited | Information & communication | 1994 |
| C21 Zone Ltd | Wholesale & retail | 2017 |
| C3RBERUS Ltd | Information & communication | 2023 |
| C4C Network Ltd | Agriculture & fishing | 2012 |
| C4S Search Ltd | Administrative & support | 2012 |
| C77 Developments Limited | Construction | 2018 |
| CA Prime Transport Ltd | Wholesale & retail | 2026 |
| Ca-Pa Services Limited | Administrative & support | 2017 |
| Cabber Consulting Limited | Information & communication | 2012 |
| Cableplus (Europe) Limited | Manufacturing | 2002 |
| Cache Media Limited | Information & communication | 2002 |
| CAD (Ckaf) Ltd | Hospitality | 2021 |
| Cade Mckeever Ltd | Financial services | 2002 |
| Cafe Chat Ltd | Hospitality | 2019 |
| Cafe Divino Swindon Ltd | Hospitality | 2019 |
| Cage Back Office Solutions Ltd | Professional & scientific | 2025 |
| Cage Business Services Ltd | Professional & scientific | 2022 |
| Cailem Consulting Limited | Professional & scientific | 2025 |
| Caitlin Courier Ltd | Transport & logistics | 2020 |
| Cake Box Swindon Limited | Wholesale & retail | 2019 |
| Cake Craft (South West) Limited | Wholesale & retail | 2017 |
| Cakk Medica Ltd | Health & social care | 2024 |
| CAL Carpentry Ltd | Construction | 2020 |
| Calabria MIA Ltd | Manufacturing | 2026 |
| Calabrothers Ltd | Hospitality | 2026 |
| Calcutt Carriages Ltd | Transport & logistics | 2023 |
| Calcutt Offices Limited | Professional & scientific | 2026 |
| Calexander Ltd | Professional & scientific | 2026 |
| Callisto Connect Limited | Professional & scientific | 2017 |
| Callow Tour Supply Ltd | Administrative & support | 2024 |
| Callowlake Associates Ltd | Professional & scientific | 2015 |
| Callum Gibbs Plumbing and Heating Ltd | Construction | 2026 |
| Calneyawco Limited | Transport & logistics | 2021 |
| Calvert Solutions Ltd | Professional & scientific | 2012 |
| Calvo Carrasco Services Ltd | Professional & scientific | 2019 |
| Cama 3 Limited | Manufacturing | 2001 |
| Cambria Court Management Company Limited | Households | 2003 |
| Cambridge English School of London (UK) Ltd | Administrative & support | 2020 |
| Cambridge Lighting Controls Ltd | Arts & recreation | 2025 |
| Camden Camping Ltd | Real estate | 2023 |
| Camens Property Services Ltd | Real estate | 2022 |
| Cameo Glass Ltd | Manufacturing | 2021 |
| Cameo Hair Salon Ltd | Other services | 2002 |
| Cameron Sports Ltd | Wholesale & retail | 2011 |
| Camjoe Care & Logistics Ltd | Transport & logistics | 2018 |
| Camology Ltd | Manufacturing | 2023 |
| Campbell Regan Property Ltd | Real estate | 2016 |
| Campbell Risk and Advisory Ltd | Professional & scientific | 2026 |
| Campbell Sport Horses Limited | Agriculture & fishing | 2018 |
| Campbell Wigs Ltd | Arts & recreation | 2019 |
| Campers & Dreams Limited | Arts & recreation | 2019 |
| Camster II Wind Farm Limited | Construction | 2020 |
| Canal Walk Management Company Limited | Households | 2003 |
| Candy Shark Ltd | Professional & scientific | 2019 |
| Cannedessence Limited | Manufacturing | 2018 |
| Cannon Travel (UK) Ltd | Administrative & support | 1978 |
| Cantillon Group Ltd | Construction | 2010 |
| Cantillon Properties Limited | Real estate | 2015 |
| Canu Health Group Ltd | Health & social care | 2025 |
| Cape Cavez Logistics UK Ltd | Transport & logistics | 2024 |
| Capella Synergy Limited | Professional & scientific | 2017 |
| Capelli Group Ltd | Other services | 2020 |
| Capewell Europe Limited | Manufacturing | 2021 |
| Capex Diagnostics Inc. Limited | Health & social care | 2018 |
| Capital C.O. Holdings Unlimited | Financial services | 2016 |
| Capital Door Stripping Ltd | Other services | 2014 |
| Capital Expo Ltd | Professional & scientific | 2017 |
| Capital One Security Limited | Administrative & support | 2024 |
| Capitan Procurement Limited | Professional & scientific | 2015 |
| Capstans Consulting Ltd | Professional & scientific | 2019 |
| Captaincarljoseph Ltd | Transport & logistics | 2025 |
| Capture Carp Limited | Wholesale & retail | 2021 |
| Capulet Leisure Limited | Hospitality | 2022 |
| Car & Kustom Ltd | Wholesale & retail | 2018 |
| Car & Truck Services (Swindon) Limited | Wholesale & retail | 1993 |
| Car Five Ltd | Wholesale & retail | 2019 |
| Caravelle Cars Limited | Wholesale & retail | 2024 |
| Carbonara (Swindon) Limited | Hospitality | 2024 |
| Card Couture Ltd | Manufacturing | 2015 |
| Card Market Limited | Wholesale & retail | 2014 |
| Cardinal Assets Limited | Real estate | 2016 |
| Cardiologica Solutions Limited | Professional & scientific | 2012 |
| Cardiorhythm Ltd | Health & social care | 2025 |
| Cardiosynchrony Ltd | Health & social care | 2017 |
| Cardpos Europe Limited | Wholesale & retail | 1999 |
| Cardview Limited | Information & communication | 2006 |
| Care 24/7 Solutions Limited | Health & social care | 2016 |
| Care Circle Swindon Ltd | Administrative & support | 2026 |
| Care Crew (Bournemouth) Limited | Administrative & support | 2022 |
| Care Crew (Bristol) Limited | Administrative & support | 2022 |
| Care Crew (Coventry) Limited | Administrative & support | 2021 |
| Care Crew (England) Limited | Administrative & support | 2023 |
| Care Crew (Exeter) Limited | Administrative & support | 2022 |
| Care Crew (Kent) Limited | Administrative & support | 2023 |
| Care Crew (Leeds) Limited | Administrative & support | 2022 |
| Care Crew (Liverpool) Limited | Administrative & support | 2022 |
| Care Crew (London) Limited | Administrative & support | 2024 |
| Care Crew (Newcastle) Limited | Administrative & support | 2023 |
| Care Crew (Nottingham) Limited | Administrative & support | 2023 |