| Birs Investments Ltd | Real estate | 2020 |
| BKR Sustainable Solutions Limited | Professional & scientific | 2011 |
| Blach Solutions Ltd | Hospitality | 2025 |
| Black & White REC Ltd | Administrative & support | 2017 |
| Black Cello Ltd | Professional & scientific | 2024 |
| Bleu Cloud Consultancy Limited | Professional & scientific | 2017 |
| Blissful Rose Limited | Wholesale & retail | 2017 |
| Blitz Gooday Limited | Professional & scientific | 2005 |
| BLOBAR67 Limited | Other services | 2017 |
| Block Evolution Ltd | Administrative & support | 2024 |
| Bloomfield Road Properties Limited | Real estate | 2026 |
| Bloor Business Solutions Ltd | Professional & scientific | 2018 |
| Blue Bottle Commissioning Ltd | Construction | 2022 |
| Blue Comet Limited | Information & communication | 2014 |
| Blue Moon Escapes Limited | Administrative & support | 2024 |
| Blue Sky Consultancy Services (London) Limited | Real estate | 2011 |
| Blueleaf Consultants Ltd | Professional & scientific | 2015 |
| Blueleaf Developments Ltd | Construction | 2013 |
| Blueleaf Real Estate Ltd | Real estate | 2020 |
| BM Landscapes Ltd | Administrative & support | 2020 |
| Bmgr Holdings Ltd | Financial services | 2024 |
| Bmgr Properties Ltd | Real estate | 2024 |
| Bollywood Dinner and Dance Limited | Hospitality | 2017 |
| Bonhomme Ltd | Real estate | 2024 |
| Bonism Limited | Information & communication | 2024 |
| Boogie BUS Limited | Information & communication | 2023 |
| Boogie BUS Music Limited | Information & communication | 2023 |
| BOOKKEEPER4YOU Ltd | Professional & scientific | 2014 |
| Booths Cafe Bar Limited | Hospitality | 2001 |
| Bossstage Ltd | Information & communication | 2023 |
| Bourne Sports Marketing Ltd | Arts & recreation | 2025 |
| Boutique DE Velo (Repairs) Limited | Other services | 2015 |
| Boutique DE Velo Limited | Wholesale & retail | 2015 |
| BOW & Co Jewellery Ltd | Manufacturing | 2019 |
| Bplms Limited | Professional & scientific | 2016 |
| Bradfords Close Residents Management Company Limited | Other services | 2009 |
| Brandstream Studios Limited | Professional & scientific | 2025 |
| Breheny Electrical Limited | Construction | 2015 |
| Bricks Estate Agents Ltd. | Real estate | 2021 |
| Bricksmart Management & Consulting Limited | Real estate | 2016 |
| Brightbms Ltd | Professional & scientific | 2023 |
| Brighton Jubilee Limited | Other services | 2003 |
| Brightstars Investment Properties Ltd | Real estate | 2019 |
| Brink Advisors Ltd | Education | 2024 |
| Broadham Green Limited | Professional & scientific | 2016 |
| Broadrich Limited | Real estate | 2012 |
| Brodie Jones Property Ltd | Real estate | 2020 |
| Brogan Gray Services Ltd | Construction | 2017 |
| Broking Software Systems Limited | Information & communication | 1988 |
| Bromead Limited | Real estate | 2013 |
| Bronz Tanning Ltd | Other services | 2024 |
| Bronzing Bay Ltd | Other services | 2007 |
| Brookdale Tree Surgery Limited | Administrative & support | 2012 |
| Brookgold Properties Limited | Real estate | 2000 |
| Brooks Estate Agents Limited | Real estate | 2010 |
| Broomfield Labour Hire Ltd | Administrative & support | 2016 |
| Brothers Recovery Ltd | Wholesale & retail | 2022 |
| Brown's Real Estate North West Ltd | Real estate | 2026 |
| Brutex Bollards Limited | Administrative & support | 2026 |
| Bstee Solutions Limited | Health & social care | 2023 |
| Buckhurst Hill Leisure Gardens CIC | Other services | 2015 |
| Buckhurst Way RTM Company Limited | Households | 2015 |
| Buckhursthill Investments Limited | Construction | 2024 |
| Buckhursthill Trading Limited | Wholesale & retail | 2016 |
| Builders Register Limited | Construction | 2017 |
| Bulletdata (2016) Limited | Information & communication | 2016 |
| Bunker Smart Ltd | Wholesale & retail | 2023 |
| Buppy JAM Limited | Professional & scientific | 2018 |
| Businessworld Ltd | Information & communication | 2015 |
| Buttonbag Ltd | Administrative & support | 2007 |
| BY Marler Ltd | Administrative & support | 2025 |
| Bytheglass Ltd | Wholesale & retail | 2019 |
| Béni Clothing Limited | Wholesale & retail | 2021 |
| C a Construction Ltd | Construction | 2018 |
| C Gabriel Limited | Real estate | 1943 |
| C J L Folkes Ltd | Professional & scientific | 2019 |
| C P Nixon Limited | | 2015 |
| C W Kelly Support Ltd | Arts & recreation | 2019 |
| C.J.E.B Consulting Limited | Professional & scientific | 2016 |
| C.T. Jones Limited | Real estate | 1997 |
| C.W Inc Limited | Information & communication | 2016 |
| Cables and Co Trading Ltd | Information & communication | 2026 |
| Cagri World Dishes Limited | Hospitality | 2019 |
| CAH Services Ltd | Administrative & support | 2023 |
| Calabash Cleaning Ltd | Administrative & support | 2018 |
| Calabash Group Services Limited | Administrative & support | 1992 |
| Call to Motion Limited | Professional & scientific | 2024 |
| Calmaxted Limited | Real estate | 2024 |
| Campbell Marson Limited | Wholesale & retail | 2007 |
| Campioni Essex Ltd | Arts & recreation | 2019 |
| Cana London Limited | Wholesale & retail | 2025 |
| Cannell Design Limited | Professional & scientific | 2022 |
| Cannonball P R Limited | Administrative & support | 2005 |
| Cannons Consulting Limited | Information & communication | 2013 |
| Cannyheat Limited | Construction | 2022 |
| Capers Catering Limited | Hospitality | 2013 |
| Capital Locums Limited | Administrative & support | 1986 |
| Capricorn Asset Management Limited | Financial services | 2025 |
| Capstans Ltd | Information & communication | 2007 |
| Care Recruitment London Ltd | Administrative & support | 2022 |