| Caballus Ltd | Arts & recreation | 2025 |
| Cabinet and Frame Limited | Manufacturing | 2023 |
| Calber Facilities Management Limited | Administrative & support | 1987 |
| Caliber Express Limited | Transport & logistics | 2025 |
| Caliss Consulting Limited | Professional & scientific | 2022 |
| Cannings Brothers Limited | Real estate | 2024 |
| Cannyhigh Limited | Wholesale & retail | 2025 |
| Cantorist Investments Limited | Professional & scientific | 2014 |
| Capability Estates Ltd | Construction | 2021 |
| Cardamom Essence Limited | Hospitality | 2023 |
| Carfax Education Limited | Education | 2010 |
| Carfax Educational Consultants Limited | Professional & scientific | 2003 |
| Carfax Educational Projects Limited | Professional & scientific | 2018 |
| Carfax Tutorial Establishment Limited | Education | 2010 |
| Caring Heart Carers Limited | Health & social care | 2013 |
| Carlos Delacruz Ltd | Professional & scientific | 2019 |
| Caroline Raine Chemical Consultancy Limited | Professional & scientific | 2023 |
| Carters Fencing and Gates Limited | Construction | 2021 |
| Casa DAS Bolitas Ltd | Hospitality | 2015 |
| Caseworks Ltd | Information & communication | 2026 |
| Castleforce Construction Limited | Construction | 2019 |
| Catalyst Trading Systems Ltd | Financial services | 2025 |
| Caversham Place Limited | Professional & scientific | 2017 |
| CB Network Infrastructure Ltd | Construction | 2023 |
| Ccfhb Limited | Arts & recreation | 2003 |
| Ceren Barbers Ltd | Other services | 2024 |
| Certbros Limited | Information & communication | 2023 |
| Certis Biolabs Limited | Professional & scientific | 2013 |
| CGT Transport Ltd | Transport & logistics | 2025 |
| Chadlington Management Company Limited | Households | 1987 |
| Chalix Limited | Other services | 2023 |
| Chalix Peppard Limited | Construction | 2023 |
| Chalix Towersey 1 Limited | Real estate | 2023 |
| Challis Corner (Sandy Lane West) Management Company Limited | Households | 2000 |
| Chance House Management Company Limited | Households | 1994 |
| Channelguru Ltd | Professional & scientific | 2018 |
| Chapman Worth Limited | Professional & scientific | 2007 |
| Charlma Well-Being Ltd | Health & social care | 2021 |
| Charlotte Manser Ceramics Ltd | Manufacturing | 2023 |
| Charlotte Woodley Ltd | Other services | 2024 |
| Charlton Baker (Wantage) Limited | Professional & scientific | 2002 |
| Charlton Environmental Limited | Administrative & support | 1999 |
| Charlton Road Management (Wantage) Company Limited | Administrative & support | 2010 |
| Charney Manor Limited | Other services | 2023 |
| Chateau VIN Limited | Professional & scientific | 2019 |
| CHD Holdings Limited | Financial services | 2021 |
| Cherrycroft Properties Ltd | Real estate | 2014 |
| Cherwell Health Care Ltd | Health & social care | 2018 |
| CHI Catalyst Ltd | Professional & scientific | 2025 |
| Chillisalsa Limited | Information & communication | 2015 |
| Chiltern Foods Wholesale Limited | Wholesale & retail | 2024 |
| Chorley Security Limited | Administrative & support | 2025 |
| Chriss Delivery Ltd | Transport & logistics | 2021 |
| Christies Care - MID & South Buckinghamshire Ltd | Health & social care | 2020 |
| Church Street 1 Limited | Real estate | 2025 |
| Church Street 2 Limited | Real estate | 2025 |
| Church Street 3 LLP | | 2026 |
| CHX Meadows Limited | Real estate | 2024 |
| CHX Verdant Limited | Real estate | 2024 |
| City Investment Properties Limited | Real estate | 1996 |
| CJB Renovations Ltd | Construction | 2025 |
| Clarity of Vision Coaching Ltd | Professional & scientific | 2024 |
| Clark’S Barbershop Limited | Other services | 2024 |
| Clean Slate Catering Ltd | Hospitality | 2025 |
| Clearsky Survey Limited | Professional & scientific | 2023 |
| Clewer Communications Limited | Administrative & support | 2024 |
| Climbing High Tree Care Ltd | Administrative & support | 2021 |
| Clinical Pocket Reference Ltd | Information & communication | 2013 |
| Cliniqual Consulting Ltd | Professional & scientific | 2025 |
| Cloud Rede Limited | Information & communication | 2019 |
| Cloudlabvapes Limited | Wholesale & retail | 2025 |
| Cloudmundi Limited | Professional & scientific | 2013 |
| Cobra Concrete Pumps Limited | Construction | 2013 |
| Codemobsterz Limited | Information & communication | 2019 |
| Colleco Limited | Financial services | 2024 |
| Collegiate AC Ltd | Real estate | 2011 |
| Collegiate Marketing Ltd | Real estate | 2017 |
| Combobulate Limited | Professional & scientific | 2015 |
| Comfy Class Ltd | Administrative & support | 2007 |
| Commercial Coachworks Limited | Wholesale & retail | 2022 |
| Complete Integration Company Ltd | Construction | 2011 |
| Conatus (UK) Limited | Professional & scientific | 2013 |
| Condor Consulting UK Limited | Professional & scientific | 2017 |
| Connect-It Media Services Ltd | Information & communication | 2025 |
| Connery & Macleod Limited | Construction | 2001 |
| Connolly Brickwork Ltd | Construction | 2018 |
| Conrad Strategic Partners Limited | Professional & scientific | 2008 |
| Conservation Architects LLP | | 2014 |
| Contency Ltd. | Wholesale & retail | 2018 |
| Contract Catering Consultants Limited | Professional & scientific | 1988 |
| Convergent Engineering Limited | Professional & scientific | 2016 |
| Cool Conversions Limited | Manufacturing | 2005 |
| Cool Products International Limited | Wholesale & retail | 2017 |
| Cooper Construction Oxon Limited | Construction | 2021 |
| Corderoy Heating & Plumbing Limited | Construction | 2013 |
| Cordial Advisory Ltd | Professional & scientific | 2026 |
| Corinium Property Ltd | Construction | 2025 |
| Cornerstone Christian Centre-Grove | Wholesale & retail | 1995 |
| Corriere Ltd | Transport & logistics | 2021 |
| Cosar Limited | Information & communication | 2012 |