| C & C Fruit & VEG Ltd | Wholesale & retail | 2011 |
| C&G Developments Ltd | Construction | 2024 |
| C.E.D Bookkeeping Services Limited | Professional & scientific | 2005 |
| C.W.Gosling Limited | Real estate | 1944 |
| C11 Services Ltd | Information & communication | 2025 |
| Cacio E Pepe Limited | Hospitality | 2025 |
| Caffeinehit Ltd | Information & communication | 2021 |
| CAH Property Management Ltd | Real estate | 2021 |
| Cain Property Solutions Ltd | Real estate | 2025 |
| Cairstan Limited | Other services | 2023 |
| Call to Action Advertising Limited | Professional & scientific | 2018 |
| Callum Sign Solutions Limited | Other services | 1998 |
| Cameron Robbins Ltd | Wholesale & retail | 2022 |
| Canaryzone Limited | Wholesale & retail | 1993 |
| Canberra Motors Limited | Extraterritorial | 1976 |
| CAP Property Services Ltd | Other services | 2017 |
| Cardigan Music Ltd | Arts & recreation | 2019 |
| Care Instinct Ltd | Health & social care | 2024 |
| Carota Ltd | Real estate | 2025 |
| Carotub Media Limited | Professional & scientific | 2023 |
| Carre Mews Residents Ltd | Households | 2011 |
| Casey's Property Holdings Limited | Real estate | 2018 |
| Caseys Removals Limited | Transport & logistics | 2024 |
| Catering Heaven (Petts Wood) Ltd | Hospitality | 2017 |
| Catford Cycling Club Limited | Arts & recreation | 2018 |
| Cator Park Limited | Professional & scientific | 2014 |
| Cederberg Enterprises Ltd | Administrative & support | 2004 |
| Ceewrite Engineering Ltd | Manufacturing | 2016 |
| Celtic Capital LLP | | 2006 |
| Cencea Business Ltd | Information & communication | 2015 |
| Centre Property Ltd | Real estate | 2017 |
| CHA Collective LLP | | 2025 |
| Chancery Education Trust | Education | 2011 |
| Chappell Interiors Limited | Manufacturing | 2024 |
| Charles Mills Construction Limited | Construction | 2020 |
| Charles Parish & Co Ltd | Real estate | 2017 |
| CHB Clearance Cleaning Contractors Ltd | Transport & logistics | 2024 |
| CHEFP87 Catering Ltd | Hospitality | 2021 |
| Chel's Fusion Ltd | Hospitality | 2023 |
| Chestnut Building & Property Maintenance Limited | Administrative & support | 2022 |
| Cheviot Lodge Management Company Limited | Households | 1984 |
| CHI Properties Ltd | Construction | 2013 |
| Chi-Lingual Limited | Extraterritorial | 2014 |
| Chisholm Gardens Limited | Administrative & support | 2024 |
| Chris James Construction (Kent) Limited | Construction | 2025 |
| Christie Audio Engineering Ltd | Information & communication | 2010 |
| Chronic Youth CIC | Manufacturing | 2024 |
| Chumley Limited | Professional & scientific | 2019 |
| Church & Co Properties Ltd | Real estate | 2025 |
| Cirona Limited | Hospitality | 2025 |
| Citizen CEO UK Limited | Professional & scientific | 2015 |
| Citywide Plumbing Ltd | Construction | 2015 |
| CJ KAM Limited | Real estate | 2017 |
| CJC Elite Trading Ltd | Wholesale & retail | 2025 |
| CJJ Subs Ltd | Hospitality | 2019 |
| Clarity Support Ltd | Professional & scientific | 2020 |
| Classic Wills Ltd | Professional & scientific | 2019 |
| CLB Advisory Limited | Information & communication | 2017 |
| CLB Commodities Ltd | Construction | 2022 |
| Clear Brew Croydon & Sutton Ltd | Administrative & support | 2020 |
| CLZ Retail Ltd | Wholesale & retail | 2023 |
| Coastal Building (Croydon) Developments Ltd | Construction | 2009 |
| Coastal Web Apps Limited | Information & communication | 2010 |
| Colbys Brewery Ltd. | Information & communication | 2015 |
| Colesy Construct Limited | Construction | 2022 |
| Collective Living Ltd | Real estate | 2024 |
| Collis-Knight Creative Ltd | Professional & scientific | 2015 |
| Comer Capital Ltd | Real estate | 2024 |
| Comfort Home Properties Limited | Real estate | 2025 |
| Command Design Ltd | Professional & scientific | 2022 |
| Command K Limited | Information & communication | 2017 |
| Commercial Window Installations Limited | Construction | 2014 |
| Commodities Traders Ltd | Wholesale & retail | 2007 |
| Compass Construction (London) Limited | Construction | 2019 |
| Compete and Connect Bromley LLP | | 2025 |
| Compete and Connect Croydon LLP | | 2025 |
| Competitive Dynamics International (United Kingdom) Limited | Professional & scientific | 1999 |
| Complete Print Solutions Limited | Information & communication | 2003 |
| Compli Software Limited | Information & communication | 2023 |
| Compton & Co Properties Limited | Real estate | 2024 |
| Computer Storage Devices Ltd | Information & communication | 2017 |
| Conductor Founders UK Limited | Information & communication | 2020 |
| Coney Hall Cycle Works Limited | Wholesale & retail | 2013 |
| Conhill Limited | Real estate | 2012 |
| Connect Automation Limited | Construction | 2020 |
| Coral Analytics Limited | Professional & scientific | 2022 |
| Coskunsu Limited | Real estate | 2019 |
| Counselling in London Ltd | Health & social care | 2014 |
| Coutts Building Contractors Limited | Construction | 2000 |
| Crafty Barbers Limited | Wholesale & retail | 2015 |
| Crafty Content Ltd | Information & communication | 2014 |
| Cray & Norton Estate Agents Limited | Real estate | 2005 |
| Crazytoad Limited | Manufacturing | 2022 |
| Create Innovation Solutions Ltd | Professional & scientific | 2005 |
| Creative Plaster Craft Ltd | Construction | 2021 |
| Creston International Limited | Extraterritorial | 1934 |
| Crispin Stores Ltd | Wholesale & retail | 2026 |
| Cristina Harber Ltd | Professional & scientific | 2023 |
| Crowd Core Group Ltd | Information & communication | 2026 |
| Crown and Comb Limited | Other services | 2025 |