| Care First Recruitment Agency Ltd | Administrative & support | 2019 |
| Caredox Limited | Health & social care | 2016 |
| Careernet Global Ltd | Administrative & support | 2013 |
| Carefree Campers Limited | Professional & scientific | 2018 |
| Caren Electrical Services Ltd | Construction | 2014 |
| CAREPOINT365 Limited | Wholesale & retail | 2020 |
| Carlstedt Consulting Limited | Information & communication | 1999 |
| Carnegie Court Management Company Limited | Real estate | 2007 |
| Caroline Greenaway Physiotherapy Limited | Health & social care | 2022 |
| Caroto Limited | Other services | 2021 |
| Carrowkeel Consulting Ltd | Professional & scientific | 2020 |
| Carys Thomas Ampofo Limited | Professional & scientific | 2011 |
| Casa Hair and Aesthetics Ltd | Other services | 2025 |
| Cascade Technology Limited | Information & communication | 1992 |
| Case Advisors Limited | Financial services | 2007 |
| Caseys Ruan Limited | Construction | 2015 |
| Cashbourne Limited | Real estate | 2016 |
| Cashcade (Ingoldmells) Limited | Other services | 1987 |
| Cassidy Glazing & Locks Ltd. | Construction | 2018 |
| Castlebar Estates Limited | Construction | 2014 |
| Catherine Priggs Education Ltd | Education | 2025 |
| Cayenne Online Limited | Wholesale & retail | 2016 |
| Cazoto Consulting Limited | Professional & scientific | 2025 |
| CBD Bureau Ltd | Wholesale & retail | 2016 |
| CBO Developments Limited | Construction | 2015 |
| CBR Consultants Limited | Professional & scientific | 2021 |
| CCO Consultancy Ltd | Professional & scientific | 2022 |
| CDB Media Ltd | Information & communication | 2022 |
| Cdgr Ltd | Real estate | 2026 |
| Cdmj Construction Limited | Construction | 2023 |
| Cdsc Limited | Professional & scientific | 2019 |
| CDT Programme Consulting Limited | Professional & scientific | 2012 |
| CDW Properties and Holdings Limited | Real estate | 2021 |
| Cedar Grace Limited | Health & social care | 2019 |
| Celadin Limited | Information & communication | 2008 |
| Centrex International Limited | Professional & scientific | 2002 |
| Cervantes Court (Northwood) Residents Company Ltd | Households | 1996 |
| Ceylonex UK Limited | Wholesale & retail | 2025 |
| CF Fitness London Limited | Transport & logistics | 2025 |
| CFG Leisure Ltd | Arts & recreation | 2017 |
| Cfs-I-Agritech Limited | Financial services | 2025 |
| CG Incorporations Limited | Administrative & support | 2011 |
| Cgcp Transport Limited | Transport & logistics | 2022 |
| Cgcp Transsport Limited | Transport & logistics | 2026 |
| Cgktrades Limited | Wholesale & retail | 2024 |
| CH Haven Care Limited | Health & social care | 2022 |
| Chalk Farm Limited | Information & communication | 2024 |
| Chambers of Neville Sorab Limited | Professional & scientific | 2025 |
| Chameleon Property Management Ltd | Real estate | 2021 |
| Champaneri Solutions Ltd | Information & communication | 2025 |
| Change-To-Be Education Ltd | Education | 2026 |
| Change-To-Be Ltd | Professional & scientific | 2018 |
| Character Developments Limited | Construction | 2013 |
| Chargemorton Limited | Real estate | 2013 |
| Charlie Oscar Delta Ltd | Wholesale & retail | 2014 |
| Charlotte Dent Limited | Information & communication | 2015 |
| Charlotte Jade Limited | Arts & recreation | 2017 |
| CHB Leadership Limited | Professional & scientific | 2020 |
| Chelsea Noir Ltd | Manufacturing | 2014 |
| Cherry Croft Management Company Limited | Households | 2001 |
| Chess Property Consultants Limited | Real estate | 2004 |
| Chess Valley Plumbing Limited | Construction | 2014 |
| Chess Valley Primary Learning Trust | Education | 2012 |
| Chesslake Limited | Professional & scientific | 2025 |
| Chestnut View Consulting Ltd | Information & communication | 2018 |
| Chethan Limited | Information & communication | 2021 |
| Chiclayo Limited | Administrative & support | 2019 |
| Childwrangler.Com Limited | Administrative & support | 2015 |
| Chiltern Bookshops Ltd | Wholesale & retail | 2006 |
| Chiltern Equestrian Limited | Agriculture & fishing | 2023 |
| Chinar Yorkshire Limited | Health & social care | 2025 |
| Chip and PIN Ltd | Administrative & support | 2020 |
| Chips and Bytes Solutions UK Limited | Information & communication | 2013 |
| Choice Properties Limited | Construction | 2015 |
| Chorleywood Common Youth Football Club Limited | Real estate | 1999 |
| Chorleywood Cricket Club Ltd | Arts & recreation | 2020 |
| Chorleywood DRY Cleaners Ltd | Other services | 2020 |
| Chorleywood Homes Ltd | Construction | 2008 |
| Chorleywood House Management Company Limited | Real estate | 1997 |
| Chorleywood Music Productions Ltd | Arts & recreation | 2022 |
| Chorleywood Trading Ltd | Financial services | 2015 |
| Chris Barlow Puppets and Creatures Ltd | Arts & recreation | 2021 |
| Chris Kane Associates Limited | Professional & scientific | 2012 |
| Christ First Watford | Other services | 2011 |
| Christobel Interiors Limited | Administrative & support | 2012 |
| Christopher Business School Limited | Education | 2019 |
| Christopher Management Consultings Limited | Professional & scientific | 2014 |
| Christopher Wray Properties Limited | Construction | 2014 |
| Chugz Limited | Professional & scientific | 2016 |
| Church Grove Management Company (NO.1) Limited | Households | 2006 |
| Church Grove Management Company (NO.2) Limited | Administrative & support | 2006 |
| Church Road (2/12A) Management Limited | Real estate | 1989 |
| Cigam Media Limited | Information & communication | 2016 |
| Cinnamon Square Limited | Wholesale & retail | 2004 |
| Circus Bars Ltd | Hospitality | 2015 |
| Citizens Advice Service in Three Rivers | Health & social care | 2004 |
| Citrineloves Ltd | Wholesale & retail | 2024 |
| City Managed Services Limited | Construction | 2018 |
| City of Gold Limited | Arts & recreation | 2013 |
| Cityscape Recruitment Limited | Administrative & support | 2009 |