| Cardioport Limited | Information & communication | 1992 |
| Carefinders Limited | Extraterritorial | 2000 |
| Caregrove Ltd | Administrative & support | 2021 |
| Carfile Systems Limited | Information & communication | 1988 |
| Carltown Limited | Real estate | 1997 |
| Carmelo's Head Start Ltd | Other services | 2002 |
| Carnegie House Letting Limited | Real estate | 2003 |
| Carnegie Properties Limited | Real estate | 2002 |
| Caroline Pattison Associates Limited | Professional & scientific | 2003 |
| Carpet Collections Limited | Wholesale & retail | 2003 |
| Carpet Rack Ltd | Wholesale & retail | 2005 |
| Carriages of Eden END Limited | Real estate | 1992 |
| Carters Waste Management Limited | Water & waste | 2019 |
| Cartwrights Advisory Services Limited | Professional & scientific | 2001 |
| Carvello Woodscutt Limited | Other services | 2001 |
| Cascadeglow Handmade Ltd | Wholesale & retail | 2025 |
| Cascades Freehold Limited | Real estate | 1989 |
| Cashew Newco Limited | Wholesale & retail | 2021 |
| Cassiobury Consultants Limited | Financial services | 1979 |
| Castledene Investments Limited | Construction | 1996 |
| Catherine Semark Ltd | Education | 2006 |
| Catton & Company Limited | Real estate | 2004 |
| Cavendish GAS Services Ltd | Construction | 2008 |
| Cavendish Housing Limited | Other services | 2006 |
| Caxton Hill Investments Limited | Real estate | 1986 |
| CBT Enterprises Ltd | Wholesale & retail | 2023 |
| Ccis Limited | Information & communication | 2007 |
| Cd&R Firefly 2 Limited | Professional & scientific | 2015 |
| Cd&R Firefly 3 Limited | Professional & scientific | 2015 |
| Cd&R Firefly 4 Limited | Professional & scientific | 2015 |
| Cd&R Firefly Bidco PLC | Professional & scientific | 2015 |
| Cedar Beaumont Foods UK Limited | Hospitality | 2019 |
| Cedar Tree Systems Ltd | Professional & scientific | 2000 |
| CEK Holdings Limited | Construction | 2001 |
| CEK Investments Ltd | Construction | 2013 |
| Celfix Labels Limited | Manufacturing | 2004 |
| Cenel Ltd | Information & communication | 1997 |
| Central Business Services Limited | Information & communication | 1999 |
| Central Drainage Services Limited | Water & waste | 2006 |
| Central Park, Stevenage, Management Co. Limited | Households | 1986 |
| Centre Travel Limited | | 1975 |
| Centroid Engineering Limited | Professional & scientific | 1998 |
| Centura Systems Limited | Real estate | 1998 |
| Cetna Consulting Ltd | Professional & scientific | 2004 |
| CF Living Ltd | Real estate | 2023 |
| CGA Trustee & Executor Company Limited | Professional & scientific | 1992 |
| Chabou Investments Ltd | Financial services | 2021 |
| Chailease International Company (UK) Limited | Professional & scientific | 2015 |
| Chalk Hill (65-67) Management Limited | Extraterritorial | 2002 |
| Chamber-Hire Limited | Extraterritorial | 2006 |
| Chancery Barr Management Limited | Real estate | 2007 |
| Charles R. Mcinnes Limited | Construction | 1978 |
| Charlotte Forbes Designs Limited | Construction | 2005 |
| Charterhouse Management Consultancy Limited | Professional & scientific | 2002 |
| Chartman Limited | Wholesale & retail | 1987 |
| Chartswood Limited | Professional & scientific | 2021 |
| Chas. a. Nethercott & SON Limited | Other services | 1944 |
| Chase Farm (Gedling) Block Management Company Limited | Households | 2019 |
| Chater and Scott Limited | Wholesale & retail | 1963 |
| CHC Commercials Limited | Wholesale & retail | 2004 |
| Cheesman Properties Limited | Real estate | 2002 |
| Chef Metehan Ltd | Hospitality | 2021 |
| Chelmscare Limited | Health & social care | 2016 |
| Cherie Cherie Ltd | Arts & recreation | 2004 |
| Chief Cosmetics Ltd | Wholesale & retail | 2014 |
| Chilling Vape Ltd | Wholesale & retail | 2025 |
| Chiltern Motor Company | | 2000 |
| Chirus Limited | Health & social care | 1995 |
| Chizema & Kabanje Ltd | Real estate | 2024 |
| Chris Dixon Isnt Limited | Information & communication | 1989 |
| Christopher's Opticians Ltd | Wholesale & retail | 2004 |
| Church of New Destiny Ltd | Other services | 2015 |
| Cidabridge Properties Limited | Professional & scientific | 2004 |
| Cidy Limited | Health & social care | 2005 |
| Cissbury Road Creative Limited | Information & communication | 2019 |
| Citadel Solutions Limited | Information & communication | 2002 |
| Clants Limited | Information & communication | 2004 |
| Clapham Road Freehold Limited | Real estate | 2007 |
| Claregate Freehold Property Ltd | Real estate | 2025 |
| Claremont Freehold Chigwell Limited | Real estate | 2004 |
| Claremont Place Management Company Limited | Households | 2002 |
| Clarendon Court Residents Association Limited | Real estate | 1991 |
| Clear Internet Solutions Limited | Information & communication | 1999 |
| Clear Software Solutions Limited | Information & communication | 1998 |
| Clearview 2000 Limited | Administrative & support | 2006 |
| Cleminson Halls (Cottingham) Management Company Limited | Households | 2012 |
| Click Click Image Services Limited | Wholesale & retail | 2006 |
| Clinic Noah Ltd | Health & social care | 2024 |
| Closefirm Limited | Real estate | 1987 |
| Cloud 22 Solutions Ltd | Information & communication | 2000 |
| Cloudy Bay Services Limited | Information & communication | 1998 |
| Clovelly House Ltd | Real estate | 2010 |
| Clymed Healthcare Ltd | Wholesale & retail | 2015 |
| CM2 Employees' Trustees Limited | Professional & scientific | 2024 |
| CMS Accommodating People Limited | Construction | 2005 |
| Cobra Industries Limited | Manufacturing | 1995 |
| Coco's PRE School Centre Limited | Education | 2006 |
| Codixo Investments Ltd | Real estate | 2016 |
| Cohesive Architecture Ltd | Information & communication | 2014 |
| Colaingrove Limited | Professional & scientific | 1974 |