| Belasyse Capital Limited | Financial services | 2022 |
| Belgrave Residential Limited | Real estate | 2009 |
| Belgrave Residential Services Limited | Real estate | 2009 |
| Believe Leotards Limited | Wholesale & retail | 2024 |
| Bella Ritchie Co Ltd | Professional & scientific | 2024 |
| Belle Landscapes Limited | Administrative & support | 2015 |
| Belle Public Relations Limited | Professional & scientific | 2014 |
| Belleatrix Limited | Administrative & support | 2006 |
| Belles Reves Homes Limited | Real estate | 2006 |
| Bellgrange Estates Limited | Real estate | 2004 |
| Bellvors Limited | Wholesale & retail | 2024 |
| Bellwalk Properties Limited | Construction | 1965 |
| Belvedere Artist Management Ltd | Arts & recreation | 2018 |
| BEN Ricketts Wealth Management Ltd | Financial services | 2018 |
| Benaka Limited | Professional & scientific | 2021 |
| Benjamin Kustow Limited | Extraterritorial | 2019 |
| Berisford Rose Limited | Transport & logistics | 2016 |
| Berkeley Business Consultants Limited | Professional & scientific | 2017 |
| Berura Investments Limited | Real estate | 2019 |
| Bespoke Home Construction Ltd | Construction | 2022 |
| Bespoke Inclusive Support Ltd | Education | 2024 |
| Best BET Media Ltd | Professional & scientific | 2025 |
| Bestoff Contracts Limited | Construction | 2009 |
| Beswick Recruitment Ltd | Administrative & support | 2018 |
| BET With Sherlock Limited | Arts & recreation | 2017 |
| Beyren Property Portfolio Ltd | Real estate | 2024 |
| Bfive Investments Limited | Arts & recreation | 2005 |
| Bhurghundii Limited | Information & communication | 2026 |
| Bianca Caplan Consultancy Ltd | Administrative & support | 2023 |
| Bibby Leisure Limited | Hospitality | 2013 |
| Bibbys Coin OP Limited | Arts & recreation | 2013 |
| Big Bounce Kingdom Ltd | Administrative & support | 2025 |
| Big Fish Academy of Darts Ltd | Education | 2026 |
| Big Technologies PLC | Professional & scientific | 2017 |
| Bigeye Ltd | Administrative & support | 2011 |
| Bildo Limited | Financial services | 2007 |
| Binson Limited | Information & communication | 2021 |
| Biodiverse Enterprise Ltd | Construction | 2024 |
| Biotip Ltd | Professional & scientific | 2019 |
| Bird Box Multi Tool Ltd | Manufacturing | 2021 |
| Birkenhead Holdings Limited | Real estate | 2020 |
| Bitesize Consulting Ltd | Professional & scientific | 2015 |
| Bittern Services Ltd | Professional & scientific | 2017 |
| Bitumex International Ltd | Wholesale & retail | 2020 |
| Bizzy Systems Limited | Extraterritorial | 1998 |
| BK Jani and Company Limited | Administrative & support | 2018 |
| Black Spot Exterior Cleaning and Maintenance Ltd | Administrative & support | 2025 |
| Blacketts Wood Properties Ltd | Real estate | 2020 |
| Blackrock Motors Limited | Wholesale & retail | 2018 |
| Blackrose Consultancy Limited | Professional & scientific | 2024 |
| Blakes Court (Management Company) Limited | Households | 1999 |
| Blaq Label Limited | Wholesale & retail | 2025 |
| Blenheim Bedrooms Limited | Construction | 2004 |
| Blissfull Limited | Real estate | 1999 |
| Blitzen Supplies Limited | Wholesale & retail | 2018 |
| Block One Hundred RTM Limited | Administrative & support | 2014 |
| Blockware Nation Limited | Information & communication | 2020 |
| Blue Chips Management Limited | Professional & scientific | 2012 |
| Blue Horizon Estates Ltd | Real estate | 2022 |
| Blue Kite Services Limited | Professional & scientific | 2020 |
| Blue Ocean Security Ltd | Transport & logistics | 2013 |
| Blue Sabio Limited | Professional & scientific | 2016 |
| Blue Skies Strategic Limited | Information & communication | 2009 |
| Blue Sky Nursing Limited | Professional & scientific | 2019 |
| Bluecore Consulting Ltd | Professional & scientific | 2025 |
| Bluedarling Limited | Arts & recreation | 2020 |
| Bluejiwa Ltd | Professional & scientific | 2013 |
| Blythe Brothers Limited | Construction | 2023 |
| Bmjk Limited | Professional & scientific | 2010 |
| BNM Logistics Limited | Transport & logistics | 2023 |
| Bobo Marketing Ltd | Professional & scientific | 2025 |
| BOI Creative Ltd | Other services | 2007 |
| Bois Holdings Limited | Professional & scientific | 1997 |
| Bois Properties Limited | Construction | 1958 |
| BOJ Global Ventures Ltd | Wholesale & retail | 2026 |
| Bombay Kitchen (Croxley) Ltd | Hospitality | 2021 |
| Bones Boxing Ltd | Arts & recreation | 2021 |
| Bonimi Interior Design Ltd | Professional & scientific | 2023 |
| Bonnyline Limited | Manufacturing | 1986 |
| Bookkeeping Cafe Ltd | Extraterritorial | 2023 |
| Bookshed Ltd | Information & communication | 2026 |
| Boozehound Films Ltd | Information & communication | 2025 |
| Bosham Shore Limited | Construction | 2006 |
| Bossie's Biltong Ltd | Wholesale & retail | 2024 |
| Boston North Digital Group Ltd | Wholesale & retail | 2025 |
| Botro Ltd | Professional & scientific | 2023 |
| Bouncing Back Recruitment Limited | Administrative & support | 2024 |
| Bowfield Limited | Real estate | 2010 |
| Bowman Group Holdings UK Limited | Financial services | 2025 |
| Boylan Films Ltd | Administrative & support | 2019 |
| Boysie London Limited | Construction | 2017 |
| BP Property Ltd | Real estate | 2023 |
| Bracken Investments Limited | Professional & scientific | 2015 |
| Brandlehow Management Company Ltd | Administrative & support | 2024 |
| Brandpage Ltd | Information & communication | 2015 |
| Brave & Bolder Ltd. | Professional & scientific | 2022 |
| Brave Pet Care Limited | Wholesale & retail | 2022 |
| Bravo Motorcars Ltd | Wholesale & retail | 2017 |
| Braycote Holdings Limited | Financial services | 2023 |
| Braycote Ltd | Real estate | 2003 |