| Buttcode Ltd | Information & communication | 2025 |
| Byrcom Limited | Information & communication | 2011 |
| BZ Cleaning Services Limited | Administrative & support | 2022 |
| C & S Car Sales Limited | Wholesale & retail | 2008 |
| C a Cook & Co Ltd | Agriculture & fishing | 2026 |
| C B Heslop and Company Limited | Professional & scientific | 2012 |
| C&L Heating and Plumbing Ltd | Construction | 2019 |
| C. Sebs Care Ltd | Public administration | 2022 |
| C.T. Property Solutions Ltd | Households | 2025 |
| Cadence & Pace Consultancy Ltd | Professional & scientific | 2020 |
| Cagan Tech Limited | Information & communication | 2017 |
| Calibre Buying Hub Ltd | Wholesale & retail | 2019 |
| Calibre Gems & Jewellery Limited | Wholesale & retail | 2011 |
| Call Brady Plumbing and Heating Limited | Construction | 2020 |
| Calleva Homes (Bishops) Ltd | Construction | 2022 |
| Calleva Homes (Bramley) Ltd | Construction | 2021 |
| Calleva Homes (Junipers) Ltd | Construction | 2023 |
| Calleva Homes and Developments (Mortimer) Ltd | Construction | 2021 |
| Camberdale Ltd | Professional & scientific | 2017 |
| Cambridge Space Associates Limited | Professional & scientific | 2015 |
| Canard Ltd | Information & communication | 2020 |
| Capability Financial Solutions Limited | Professional & scientific | 2019 |
| Capamore Holdings Limited | Real estate | 2026 |
| Careboodle Consultancy Limited | Professional & scientific | 2022 |
| Carey Electrical Ltd | Construction | 2011 |
| Carlina Management Limited | Administrative & support | 1994 |
| Carlton Fisher Limited | Real estate | 2011 |
| Caroline Compton LLP | | 2025 |
| Caroline Nixon Photography Ltd | Professional & scientific | 2018 |
| Casa Bella Blinds Ltd | Other services | 2013 |
| Casram Corp Ltd | Wholesale & retail | 2023 |
| Catcoomb Enterprises Limited | Hospitality | 2019 |
| Catherine Hall Architecture Limited | Professional & scientific | 2019 |
| Cathy Berry Driving Instructor Ltd | Education | 2025 |
| Cazmak Services Ltd | Professional & scientific | 2012 |
| CBS Architectural Ironmongery Ltd | Wholesale & retail | 2015 |
| CC Protect Ltd | Administrative & support | 2025 |
| CC Survey Services Ltd | Professional & scientific | 2017 |
| CCB Design Limited | Professional & scientific | 2012 |
| CCB Farnham Ltd | Wholesale & retail | 2019 |
| CDB Financial Services Limited | Financial services | 2017 |
| Celeste Consultants Ltd | Professional & scientific | 2016 |
| Celeste Homes Ltd | Real estate | 2017 |
| Celestron Global Limited | Wholesale & retail | 2014 |
| Central Conveyor Belting Services Ltd | Manufacturing | 1986 |
| Central Heating Advice Service Limited | Construction | 2015 |
| Certi Plumbing Services Ltd | Construction | 2024 |
| Cfay Ltd | Administrative & support | 2023 |
| CG Roofing Specialists Ltd | Construction | 2021 |
| CGA Consultancy Services Ltd | Professional & scientific | 2021 |
| Chadawn Ltd | Wholesale & retail | 2025 |
| Champlain Reach RTM Company Limited | Households | 2010 |
| Chapel Court Residents Association (Thatcham) Limited | Households | 2000 |
| Charles Oliver Cars Ltd | Wholesale & retail | 2021 |
| Charles Percy Sebastian Limited | Real estate | 2017 |
| Charly Edwards Equestrian Ltd | Administrative & support | 2018 |
| Cheam School Educational Trust | Education | 1984 |
| Cheam Trading Ltd | Administrative & support | 2016 |
| Cheftec Ltd | Manufacturing | 2016 |
| Chenwood Ltd | Wholesale & retail | 2025 |
| Cherry Financial Services Ltd | Professional & scientific | 2026 |
| Cherry Orchard Limited | Construction | 2026 |
| Cherry Tree Stables Limited | Arts & recreation | 2016 |
| Chieveley Roofing Services Ltd | Construction | 2026 |
| Chiltern Enterprise Centre Limited | Real estate | 2005 |
| China Kitchen (Thatcham) Limited | Hospitality | 2024 |
| Chirispa Limited | Health & social care | 2019 |
| Choice Hacking Ltd | Information & communication | 2021 |
| Chubb Grand Designs Ltd | Construction | 2022 |
| Church Close (Thatcham) Common Area Management Company Limited | Administrative & support | 2010 |
| Church Gate Thatcham Management Limited | Administrative & support | 2011 |
| Church Street (Theale) Management Company Limited | Construction | 2011 |
| Cistus Limited | Construction | 2011 |
| City Change Management Limited | Administrative & support | 2008 |
| CJF Electrical Services Ltd | Construction | 2024 |
| Cjfe Property Ltd | Real estate | 2020 |
| CJK Engineering Solutions Limited | Information & communication | 2019 |
| Claire Elizabeth Boulter Limited | Information & communication | 2018 |
| Claire Willsher Ltd | Health & social care | 2022 |
| Claridges Plumbing & Heating Services Limited | Construction | 2007 |
| Claritas Procurement Limited | Administrative & support | 2021 |
| Clarito Software Ltd | Information & communication | 2026 |
| Clark’S Cars and Commercials Limited | Wholesale & retail | 2025 |
| Classic Car Buyer UK Ltd | Wholesale & retail | 2026 |
| Classic/Vintage Truck Restoration Ltd | Wholesale & retail | 2017 |
| Clean Difference (Newbury) Ltd | Administrative & support | 2024 |
| Clere Golf Tech Ltd | Information & communication | 2023 |
| Clifford's Decorating & Refurbs Limited | Construction | 2010 |
| Clinical Wellbeing Ltd | Education | 2021 |
| Cloud Cells Consulting Ltd | Information & communication | 2013 |
| Cloud Properties Limited | Administrative & support | 2013 |
| CM26 Ltd | Construction | 2022 |
| CN Newbury Ltd | Education | 2020 |
| Coach House Vets Limited | Professional & scientific | 2005 |
| Cocktail Runner Ltd | Wholesale & retail | 2021 |
| Codegarage Ltd | Information & communication | 2018 |
| Coffee Mugs and More Limited | Wholesale & retail | 2005 |
| Colbury Accounting Ltd | Professional & scientific | 2010 |
| Collaboration Junkie Limited | Professional & scientific | 2019 |
| Colthrop Holdings Limited | Financial services | 2011 |