| Brimsdown Property Ltd | Real estate | 2023 |
| Bristol Commercial Vehicles Ltd | Wholesale & retail | 2026 |
| Bristow Installations Ltd | Construction | 2015 |
| Brit Interiors Limited | Construction | 2004 |
| Britannia General Maintenance Ltd | Construction | 2014 |
| Broadfields Group Ltd | Financial services | 2026 |
| Broadway Glow Ltd | Other services | 2025 |
| Bronni LLP | | 2013 |
| Brook Mill Property Management LLP | | 2009 |
| Brooke Grove Residence Limited | Households | 2018 |
| Brookmans & Berkeley Wealth Ltd. | Financial services | 2014 |
| Brookmans Group Limited | Water & waste | 2019 |
| Brookmans Locations Ltd | Information & communication | 2014 |
| Broughton Lodge Care Home Limited | Health & social care | 2016 |
| Brownlow Enterprises Limited | Health & social care | 1996 |
| Broxbourne Alliance PCN Ltd | Health & social care | 2021 |
| BRP Management Ltd | Professional & scientific | 2018 |
| BRR Trading Limited | Administrative & support | 2016 |
| Brunswick Press Limited | Manufacturing | 2020 |
| Bryn WEN Ltd | Real estate | 2024 |
| BS Housings Ltd | Real estate | 2024 |
| BSC Property Services Ltd | Construction | 2025 |
| BSV Park Homes Ltd | Real estate | 2023 |
| BSW Ventilation Ltd | Manufacturing | 2026 |
| Bubbletrukk Ltd | Hospitality | 2023 |
| Buckenham Locksmiths Ltd | Other services | 2017 |
| Buffbar Limited | Other services | 2023 |
| Build Finance Limited | Financial services | 2017 |
| Build Trust Group Limited | Financial services | 2024 |
| Building & Trade Ltd | Administrative & support | 2015 |
| Building Your Spaces Ltd | Construction | 2015 |
| Buildsmart Advisory Ltd | Administrative & support | 2025 |
| Built Environment and Architecture Media Limited | Information & communication | 2019 |
| Bulgarian American Foods Limited | Administrative & support | 2005 |
| Bunny Lake Design Limited | Professional & scientific | 2021 |
| Burdett House Ltd | Construction | 2015 |
| Burgage Properties Limited | Real estate | 1976 |
| Burrows Property Ltd | Administrative & support | 2018 |
| Bush Hill Flooring Limited | Construction | 2017 |
| Buyithomes Limited | Real estate | 2013 |
| Buyyourhomes (Leaseholds) Ltd | Real estate | 2023 |
| Buyyourhomes Ltd | Construction | 2018 |
| Bvtr Property Limited | Real estate | 2025 |
| BY Belovd Ltd | Extraterritorial | 2023 |
| BY Scheme Ltd | Professional & scientific | 2021 |
| Bycullah Investments Limited | Real estate | 2024 |
| Byng Tech Ltd | Information & communication | 2017 |
| C & C Associates Ltd | Financial services | 2025 |
| C & C Motor Vehicle Repairs Limited | Wholesale & retail | 2020 |
| C J Hurst Consultancy Limited | Other services | 2018 |
| C P Christou LLP | | 2010 |
| C R R Haulage Limited | Extraterritorial | 2020 |
| C&J Vehicle Logistics & Recovery Ltd | Transport & logistics | 2025 |
| C&N Consulting Ltd | Professional & scientific | 2014 |
| C. a. Savvides & Co Limited | Extraterritorial | 2004 |
| C. B. International Company Limited | Information & communication | 1995 |
| C.P.Management Limited | Administrative & support | 1969 |
| C1 Construction & Development Services Ltd | Construction | 2016 |
| C2UNLOCKS Limited | Administrative & support | 2024 |
| CA (UK) Limited | Professional & scientific | 1991 |
| Cabaret Limited | Other services | 2026 |
| Cadenza Holdings Ltd | Real estate | 2022 |
| Cadmore Auctions Ltd | Wholesale & retail | 2020 |
| Caffeine London Limited | Other services | 2017 |
| Callover Limited | Real estate | 1997 |
| Cally and Cross Ltd | Wholesale & retail | 2023 |
| Calvin Brown Property Services Limited | Real estate | 2019 |
| Calvin Brown Transport Services Limited | Transport & logistics | 2022 |
| Cambridge Electric Transport Limited | Wholesale & retail | 2017 |
| Cambridge Street Holdco Ltd | Real estate | 2020 |
| Camden Edition Limited | Hospitality | 2017 |
| Cami Builders Ltd | Construction | 2025 |
| Campden House Court RTM Company Ltd | Households | 2024 |
| Candlestick Holdings Ltd | Professional & scientific | 2019 |
| Canex Financial Services Ltd | Information & communication | 2008 |
| Cannonball Films Limited | Administrative & support | 2006 |
| Canonbury Antiques Limited | Wholesale & retail | 1971 |
| Canonbury Builders Merchants Limited | Wholesale & retail | 2000 |
| Cansu Ltd | Hospitality | 2025 |
| Canterbury Park (High Cross) Management Company Limited | Households | 2014 |
| Canterbury Place (Grays) Management Company Limited | Households | 1992 |
| Capacity Capital Ltd | Other services | 2020 |
| Capalytix Ltd | Information & communication | 2011 |
| Capella Property Services Ltd | Real estate | 2026 |
| Capital D Investment Limited | Real estate | 2025 |
| Capital Financial Services Limited | Financial services | 2019 |
| Capitol Estates UK Limited | Real estate | 2007 |
| Capitol Management Limited | Real estate | 1999 |
| Capitol Management UK Limited | Administrative & support | 2007 |
| Caprera Investments Limited | Real estate | 2026 |
| Captain Kidd's Pirate Experience Ltd | Arts & recreation | 2019 |
| Captain Kidd's Ship Adventure Galley Ltd | Education | 2012 |
| Car Club Direct Limited | Financial services | 2014 |
| Card Holdings Limited | Information & communication | 2021 |
| Cardboard Creative Limited | Information & communication | 2019 |
| Cardiac Safety Consultants Ltd | Professional & scientific | 2008 |
| Cardioplus International Academy Ltd | Education | 2024 |
| Care for Freedom Limited | Health & social care | 2012 |
| CARE406 Ltd | Administrative & support | 2018 |
| Carlos @ Judges Limited | Hospitality | 2020 |