| Buckingham Court Property Management Limited | Real estate | 2000 |
| Bucks Barbers Limited | Other services | 2013 |
| Budding Partnership Ltd | Arts & recreation | 2022 |
| Budinvest Carpenter Ltd | Construction | 2024 |
| Build and Grow CIC | Agriculture & fishing | 2024 |
| Build From Design Limited | Construction | 2021 |
| Build OUT & in Ltd | Construction | 2025 |
| Build Track PAY Limited | Administrative & support | 2026 |
| Builders Merchant Online Group Ltd | Construction | 2025 |
| Building Cladding & Safety Scheme Advisors Ltd | Other services | 2025 |
| Building Systems Profiling Limited | Manufacturing | 2025 |
| Buildit (SPV) Ltd | Real estate | 2023 |
| Bulk Fuel Solutions Limited | Transport & logistics | 2011 |
| Bullen Hall Limited | Construction | 2015 |
| Bullen Roofing Ltd | Construction | 2021 |
| Bullman Marine Supplies & Containers Limited | Wholesale & retail | 1975 |
| Bullman Self Storage & Archive Centres Limited | Professional & scientific | 2000 |
| Bullman Welding Limited | Wholesale & retail | 2000 |
| Bulls Construction Ltd | Construction | 2013 |
| Bultex Limited | Construction | 2026 |
| Bungalow Homes Developments Ltd | Real estate | 2024 |
| Bunsbros Europe Ltd | Hospitality | 2021 |
| Bunting Developments Limited | Financial services | 2025 |
| Burchell Group Limited | Professional & scientific | 2023 |
| Burdett Trading Co. Limited | Financial services | 1988 |
| Burlington & Co. Transport Management & Events Ltd | Transport & logistics | 2010 |
| Burlington Apartments Limited | Real estate | 2020 |
| Burney Drive(Block A)Management Company Limited | Real estate | 1984 |
| Burnox Ltd | Construction | 2026 |
| Burrsmid Developments Limited | Construction | 2006 |
| Bushberry Properties Limited | Real estate | 2021 |
| Bushmead Properties Limited | Real estate | 1987 |
| Business Accountants Services Ltd | Professional & scientific | 2016 |
| Business Computer Services U.K. Limited | Information & communication | 1998 |
| Business Excellence Europe Limited | Information & communication | 2021 |
| Business Rates Relief Limited | Professional & scientific | 2023 |
| Buwere Limited | Construction | 2026 |
| BV Building Services Ltd | Construction | 2018 |
| BY HIS Strength Limited | Wholesale & retail | 2025 |
| Byerley Turk E-Commerce Logistics Ltd | Wholesale & retail | 2022 |
| BYF Transport, Logistics & Supplies Limited | Transport & logistics | 2016 |
| C & K Stores Limited | Wholesale & retail | 2003 |
| C a Products Limited | Other services | 2005 |
| C C Cooling Ltd | Construction | 2017 |
| C F Heating & Plumbing Limited | Construction | 2016 |
| C FOX Property Holdings Ltd | Real estate | 2019 |
| C M Metals Limited | Other services | 2020 |
| C Petrou Stunts Ltd | Arts & recreation | 2018 |
| C&A Management Ltd | Construction | 2020 |
| C&E Fire Consultants Limited | Professional & scientific | 2018 |
| C&M Electrical (Essex) Limited | Construction | 2022 |
| C&N Mechanical and Electrical Ltd | Construction | 2021 |
| C&S Landscape & Gardens Ltd | Administrative & support | 2025 |
| C.A. Contracts Services Ltd | Administrative & support | 2023 |
| C.Alexander Education Ltd | Education | 2015 |
| C.B. Buildings and Claims Limited | Financial services | 2013 |
| C.J. Engineering (Southern) Ltd | Wholesale & retail | 2025 |
| C.P.Roofing Ltd | Construction | 2010 |
| C.S Music Production Ltd | Information & communication | 2020 |
| Cabrix Construction Limited | Construction | 2026 |
| Caestu Sports Limited | Wholesale & retail | 2024 |
| Cafe Caribbean (London) Ltd | Hospitality | 2016 |
| Cai&Co Ltd | Professional & scientific | 2025 |
| Calculus Accountants and Tax Advisers Limited | Professional & scientific | 2008 |
| Calicojack Limited | Real estate | 2025 |
| Callum Martin Energy Ltd | Professional & scientific | 2025 |
| Calm Productions Limited | Wholesale & retail | 2003 |
| Calverley Property LLP | | 2020 |
| Camanchi Developments Limited | Administrative & support | 2011 |
| Camanchi Holdings Limited | Real estate | 2018 |
| Camanchi Management Limited | Construction | 2024 |
| Camber Security Systems Limited | Administrative & support | 2016 |
| Cambridge Court (Hackney) RTM Company Limited | Real estate | 2020 |
| Cambridge Innovision Limited | Information & communication | 2003 |
| Cambridge Thoughtware Limited | Administrative & support | 2010 |
| Camden Laundry Services (U.K.) Ltd | Other services | 2017 |
| Camden Vision Limited | Construction | 2024 |
| Camlay Property Services Limited | Administrative & support | 2016 |
| Campioni Events Limited | Arts & recreation | 2016 |
| Campling Foods Limited | Hospitality | 2022 |
| Canchari Transport Ltd | Transport & logistics | 2025 |
| CANNUL8 Ltd | Manufacturing | 2020 |
| Canuk Enterprises Ltd | Construction | 2025 |
| Capa Investments Limited | Financial services | 2014 |
| Capcg Ltd | Construction | 2012 |
| Capewall Limited | Information & communication | 1978 |
| Capital 18 Limited | Real estate | 2021 |
| Capital 19 Limited | Financial services | 2021 |
| Capital 25 Limited | Administrative & support | 2025 |
| Capital 26 Limited | Other services | 2024 |
| Capital Business Consultants Limited | Professional & scientific | 2018 |
| Capital Catering & Hire Ltd | Hospitality | 2018 |
| Capital Collections Ltd | Wholesale & retail | 2025 |
| Capital Land Estates Ltd | Real estate | 2025 |
| Capital Steam Installations Ltd | Manufacturing | 2014 |
| Capital Talks LLP | | 2018 |
| Capital Veneer Company Limited | Wholesale & retail | 1988 |
| Capital Veneer Investment Ltd | Financial services | 2025 |
| Capitalnow Commercial Finance Ltd | Financial services | 2025 |
| Capriano Limited | Financial services | 2017 |