| Carbon Crystal Limited | Information & communication | 2012 |
| Card Media International Limited | Professional & scientific | 2001 |
| Cardinal Clinic Ltd | Extraterritorial | 2016 |
| Cardno & Associates Limited | Professional & scientific | 2010 |
| Care at Home Reading Limited | Health & social care | 2014 |
| Care Concept - Solutions Limited | Public administration | 2019 |
| Care Fountain Ltd | Health & social care | 2023 |
| Care Solutions & Management Limited | Professional & scientific | 2014 |
| Care With Actions Limited | Administrative & support | 2022 |
| Careersense Ltd | Education | 2011 |
| Carefusion U.K. 305 Limited | Manufacturing | 1994 |
| Cargil Solutions Ltd | Wholesale & retail | 2009 |
| Cargo Management Solutions Ltd | Professional & scientific | 2022 |
| Cargonet Limited | Transport & logistics | 2013 |
| Caribbiz Enterprise Ltd. | Transport & logistics | 2024 |
| Cariso Properties Limited | Real estate | 2025 |
| Carita Express Limited | Other services | 2018 |
| Carlin Place RTM Company Limited | Households | 2008 |
| Carnasserie Limited | Professional & scientific | 2021 |
| Caroline York Limited | Manufacturing | 2002 |
| Carpe Diem JL Ltd | Wholesale & retail | 2020 |
| Carpetage Ltd | Construction | 2017 |
| Carrera Aviation Ltd | Transport & logistics | 2023 |
| Carrera Carpentry & Joinery Ltd | Construction | 2012 |
| Carrie’S Childminding Ltd | Health & social care | 2024 |
| Carrs Automotive Engineering Ltd | Wholesale & retail | 2014 |
| Cary Education Limited | Education | 2016 |
| Cary On-Entertainment Limited | Education | 2016 |
| Carzfix Ltd | Wholesale & retail | 2025 |
| Casamare Limited | Real estate | 2020 |
| Case Heating & Plumbing Ltd | Construction | 2021 |
| Cassio Business Solutions Ltd | Wholesale & retail | 2024 |
| Castle Lodge Management Company Limited | Households | 1983 |
| Castle View (Newbury) Management Company Limited | Households | 2015 |
| Castlecomms Tech Ltd | Information & communication | 2024 |
| Castlecommskit Ltd | Information & communication | 2016 |
| Castles Property Services Limited | Real estate | 2004 |
| Castlewoods Estates & Properties Limited | Real estate | 2021 |
| Cat Executive Services Ltd | Professional & scientific | 2020 |
| Catarina Pimentel Ltd | Health & social care | 2024 |
| Catch the Ball Productions Ltd | Information & communication | 2010 |
| Caterprompt Ltd | Manufacturing | 2016 |
| Cathedral Studios Limited | Arts & recreation | 2022 |
| Cause an Effect Consulting Limited | Professional & scientific | 2003 |
| Causeway Entertainment Limited | Information & communication | 2023 |
| Cautim Ltd | Information & communication | 2011 |
| Caversham Bridge Consulting Ltd | Professional & scientific | 2009 |
| Caversham Flooring Company Limited | Construction | 2001 |
| Caversham Properties (UK) Limited | Real estate | 2006 |
| Cavity Dental Staff Agency Ltd | Extraterritorial | 2025 |
| Cavity Dental Staff Limited | Administrative & support | 2007 |
| Cavity Dental Training Ltd | Extraterritorial | 2025 |
| CB Patch Ltd | Manufacturing | 2024 |
| CB Rescue Cream Ltd | Wholesale & retail | 2024 |
| CBD Health Foods Ltd | Manufacturing | 2016 |
| CC Coaching Limited | Other services | 2013 |
| CC Solar Services Ltd | Construction | 2023 |
| CCD Bradbury Investments Ltd | Households | 2024 |
| CDE Solutions Limited | Construction | 2011 |
| CDP Contracting Ltd | Professional & scientific | 2022 |
| Ceahlau Assessments LLP | | 2017 |
| Ceceil's Cheese and Charcuterie Limited | Hospitality | 2024 |
| Cedar Court Management Company (Datchet) Limited | Households | 2005 |
| Cedar Crest Estates Ltd | Real estate | 2026 |
| Cedarwest Property and Relocations Ltd | Construction | 2025 |
| Cees Fasteners Limited | Wholesale & retail | 2015 |
| Ceilings & Walls M2 Limited | Construction | 2009 |
| Celef Audio International Limited | Wholesale & retail | 1975 |
| Celeste Housing Ltd | Hospitality | 2025 |
| Celestial Moon Crystals Ltd | Wholesale & retail | 2022 |
| Cell EVS Ltd | Wholesale & retail | 2023 |
| Cellbase Limited | Professional & scientific | 2012 |
| Cellia MD Ltd | Health & social care | 2025 |
| Cellular Services Limited | Manufacturing | 1986 |
| Cennd Collective Ltd | Wholesale & retail | 2025 |
| Centaur Holdings Ltd | Real estate | 2022 |
| Centaurus Advisory Partners Limited | Professional & scientific | 2022 |
| Century Roofing Berkshire Limited | Construction | 2022 |
| Cerdren Ltd | Professional & scientific | 2010 |
| Ceriter Investments 2 Limited | Professional & scientific | 2018 |
| Ceriter Investments 3 Limited | Professional & scientific | 2018 |
| Cestra Ltd | Information & communication | 2025 |
| Ceylon Copper Ltd | Wholesale & retail | 2022 |
| CG Global Freight Limited | Transport & logistics | 2021 |
| CGM Sales Consultancy Ltd | Professional & scientific | 2024 |
| Chadha Realtors Ltd | Real estate | 2022 |
| Chadha Tech Ltd | Information & communication | 2019 |
| Chae Time Limited | Hospitality | 2024 |
| Chalk Bars and Venues Ltd | Hospitality | 2022 |
| Chalk in the Park Ltd | Hospitality | 2022 |
| Chalk Restaurants Limited | Hospitality | 2020 |
| Chalkhouse Caversham Ltd | Health & social care | 2025 |
| Chalkhouse Childcare Services Limited | Education | 2011 |
| Chalkhouse Henley Ltd | Health & social care | 2022 |
| Chalkhouse Nursery Group Limited | Financial services | 2024 |
| Chalkhouse Nursery Waterside Ltd | Health & social care | 2023 |
| Chalkhouse Reading Limited | Health & social care | 2025 |
| Champ Creative Solutions Ltd | Professional & scientific | 2025 |
| Changed Limited | Professional & scientific | 2015 |
| Channel Consult Limited | Extraterritorial | 2012 |