| Cintelliq Limited | Information & communication | 2002 |
| Cintra Language Services Group Ltd | Professional & scientific | 1997 |
| Ciompo Ventures Ltd | Arts & recreation | 2017 |
| Cipolla Consultants Ltd | Professional & scientific | 2022 |
| Cipriani Developments Ltd | Construction | 2025 |
| Cipriani Plumbing and Services Ltd | Construction | 2018 |
| Circ KIT Limited | Professional & scientific | 2012 |
| Circadia Living Ltd | Real estate | 2025 |
| Circle Connect Co., Limited | Information & communication | 2025 |
| Circle MED Ltd | Health & social care | 2023 |
| Circltech Limited | Professional & scientific | 2024 |
| Circuit Solutions Limited | Extraterritorial | 2007 |
| Ciris Healthcare Limited | Information & communication | 1999 |
| CIS Division Limited | Information & communication | 2012 |
| Ciso Helper Limited | Information & communication | 2015 |
| Citadel Security Services Ltd | Administrative & support | 2018 |
| Citinest Property Ltd | Real estate | 2025 |
| Citizens' Card Alliance Limited | Other services | 2004 |
| Citrex Limited | Education | 2014 |
| Citriodora Limited | Health & social care | 2020 |
| City and Airport Cabs Ltd | Transport & logistics | 2026 |
| City Care Services Limited | Health & social care | 2000 |
| City Church (Cambridge) | Other services | 1999 |
| City Heights Cambridge Limited | Households | 2004 |
| City of Cambridge Education Foundation | Education | 2003 |
| City of Cambridge Education Limited | Education | 2006 |
| City of Cambridge Rowing Club Ltd | Arts & recreation | 2015 |
| City Quarter Residents Management Company Limited | Administrative & support | 2006 |
| City Road (Cambridge) LLP | | 2008 |
| City Roofing Repairs Ltd | Construction | 2025 |
| City View Digital Media Ltd | Information & communication | 2002 |
| Citybay Properties Limited | Real estate | 2008 |
| Citycomfy Ltd | Real estate | 2025 |
| Citygate Property Partners Limited | Real estate | 2014 |
| Citystay Limited | Hospitality | 2008 |
| Citystay Property Agents Ltd | Real estate | 2024 |
| Civic Healthcare Limited | Public administration | 2021 |
| Civilistix Ltd | Professional & scientific | 2019 |
| Civilizations in Contact | Education | 2012 |
| Cizlikm Ltd | Manufacturing | 2023 |
| CJ Cambs Ltd | Hospitality | 2025 |
| CJ Ducker Media Limited | Information & communication | 2023 |
| CJ Honest Co., Ltd | Wholesale & retail | 2014 |
| CJB Property Investment Limited | Households | 2018 |
| CJJ Partners UK Limited | Information & communication | 2023 |
| CJL Real Estate Ltd | Real estate | 2022 |
| CJP Consulting Services Limited | Professional & scientific | 2017 |
| Cjsg Ltd | Administrative & support | 2022 |
| Cjtrading (Cambridge) Limited | Hospitality | 2020 |
| CJV Dining Ltd | Hospitality | 2019 |
| CK Marine Service Ltd | Extraterritorial | 2016 |
| Cklg Group Ltd | Financial services | 2021 |
| Cklg Limited | Professional & scientific | 2007 |
| Ckmb Limited | Health & social care | 2022 |
| CKR Consultancy Ltd | Professional & scientific | 2022 |
| CL Nord Ltd | Arts & recreation | 2021 |
| Clac Limited | Education | 2007 |
| Clan Gorm Ltd | Real estate | 2025 |
| Clara Energy Ltd | Manufacturing | 2015 |
| Clare College Conferences Ltd. | Hospitality | 2012 |
| Clare College Limited | Construction | 1992 |
| Clare Court (Milton) RTO Company Limited | Households | 2026 |
| Clare Court Management Company (Milton) Ltd | Households | 2024 |
| Clare HAY Ltd. | Information & communication | 2019 |
| Clare Hopkins Limited | Health & social care | 2002 |
| Clare Management Services Limited | Real estate | 1993 |
| Clare Nunn Limited | Other services | 2014 |
| Clarebout Romain Ltd | Manufacturing | 2025 |
| Clarendon Arms Catering Ltd | Hospitality | 2025 |
| Clarendon House (Fleet) M. C. Limited | Households | 1994 |
| Clarendon Information Limited | Financial services | 1988 |
| Clarient Global Limited | Other services | 2025 |
| Claritrio Technology Ltd | Wholesale & retail | 2026 |
| Clarity (EM) Limited | Extraterritorial | 2014 |
| Clarity Cleanse Ltd | Administrative & support | 2025 |
| Clarity Coaching Limited | Professional & scientific | 2004 |
| Clarity Discovery Invention Ltd | Professional & scientific | 2025 |
| Clarity Engineering Design Ltd | Professional & scientific | 2018 |
| Clarity Engineering Services Ltd | Professional & scientific | 2025 |
| Clarity Health Group Ltd | Professional & scientific | 2025 |
| Clarity Sensors Limited | Professional & scientific | 2022 |
| Clark Antibodies Ltd. | Professional & scientific | 2009 |
| Clark Bradbury Ltd. | Professional & scientific | 2009 |
| Clarks Garage Limited | Wholesale & retail | 2004 |
| Clarum Ltd | Information & communication | 2024 |
| Clasina Limited | Real estate | 2017 |
| Class Hockey Limited | Arts & recreation | 2018 |
| Classic and Prestige Limited | Wholesale & retail | 2024 |
| Classic Hair Style Limited | Other services | 2016 |
| Classico Latino Music Limited | Arts & recreation | 2017 |
| Claudiamcare Ltd | Transport & logistics | 2019 |
| Clay Connect Art Ltd | Manufacturing | 2024 |
| Clay Farm Advisors Limited | Professional & scientific | 2026 |
| CLE EN Main Corp., Ltd | Extraterritorial | 2014 |
| Clean Power Systems (UK) Limited | Manufacturing | 2024 |
| Clean Vision Homes Limited | Administrative & support | 2025 |
| Cleanbridge Ltd | Administrative & support | 2025 |
| Cleaners Union Ltd | Administrative & support | 2021 |
| Cleaning Eagles Ltd | Administrative & support | 2026 |
| Cleaning Relief Ltd | Administrative & support | 2025 |