| BMH Estates Limited | Real estate | 2020 |
| BMI Trading Group Ltd | Wholesale & retail | 2026 |
| BMJ Healthcare Company Limited | Health & social care | 2018 |
| Bmks Ltd | Health & social care | 2014 |
| BMS Control Solutions Ltd | Manufacturing | 2025 |
| BMS Letting and Property Management Ltd | Real estate | 2025 |
| BMT Transport Ltd | Transport & logistics | 2026 |
| BN Dhaliwal Property Limited | Real estate | 2021 |
| BN Dwellings Ltd | Real estate | 2021 |
| BN HCW Southampton Ltd | Wholesale & retail | 2025 |
| BN Logistics & General Trading Ltd | Wholesale & retail | 2026 |
| Bnf.Pharma Limited | Education | 2025 |
| BNR UK Holdings Ltd | Wholesale & retail | 2022 |
| BNV Consultants Limited | Professional & scientific | 2014 |
| BOB Breen Associates Ltd | Professional & scientific | 2019 |
| BOB Burge Limited | Transport & logistics | 1965 |
| Bobb Technologies Limited | Information & communication | 2022 |
| Bobbala Tech Innovations Limited | Information & communication | 2025 |
| Bober Builders Ltd | Wholesale & retail | 2024 |
| Bobit Limited | Wholesale & retail | 2024 |
| Bobo (Slough) Limited | Construction | 2015 |
| Bocco Commercials Ltd | Administrative & support | 2013 |
| Bodebose Ltd | Construction | 2014 |
| Bodiam Productions Ltd | Information & communication | 2022 |
| Bodisync Ltd | Health & social care | 2019 |
| Bodla Transport Ltd | Wholesale & retail | 2026 |
| Bodmin Dental Care Limited | Health & social care | 2007 |
| Body Re:Shape Studio Ltd | Other services | 2026 |
| Body Shop Slough Ltd | Wholesale & retail | 2022 |
| Bodyverse Clinic Limited | Health & social care | 2020 |
| Boen Trading Limited | Wholesale & retail | 2023 |
| BOG Bespoke Services Limited | Transport & logistics | 2025 |
| Bogackimetalart Ltd | Construction | 2024 |
| Bognor Regis Development Ltd | Real estate | 2020 |
| Bohapp UK Services Limited | Health & social care | 2018 |
| Boiler Pointer Ltd | Construction | 2018 |
| Boilertec Ltd | Other services | 2007 |
| Bokan Enterprise Limited | Administrative & support | 2017 |
| Boland Estates Ltd | Real estate | 2018 |
| Bold Rare Minds Limited | Administrative & support | 2025 |
| Bold Rose Limited | Administrative & support | 2024 |
| Bollywood Club Limited | Hospitality | 2025 |
| Bollywood Collection Ltd | Wholesale & retail | 2018 |
| Boltec Properties Limited | Real estate | 2025 |
| Bombay Bowl Ltd | Hospitality | 2021 |
| Bombay Chiswick Ltd | Hospitality | 2026 |
| Bomberk Ltd | Extraterritorial | 2021 |
| Bond 007 Ltd | Transport & logistics | 2016 |
| Bondoc Construct Ltd | Construction | 2025 |
| Bong Thai Restaurant Ltd | Hospitality | 2023 |
| Bongai Enterprise Limited | Health & social care | 2022 |
| Bonnie Tech Ltd | Information & communication | 2020 |
| Boogie Hospitality Ltd | Hospitality | 2025 |
| Book Airport Transfers Ltd | Transport & logistics | 2013 |
| Book Avenue Limited | Administrative & support | 2023 |
| Bookkeeping and Payroll Office Ltd | Professional & scientific | 2022 |
| Books 4 Business Limited | Professional & scientific | 2005 |
| Boom Boom Services Ltd | Information & communication | 2026 |
| Bootble Ltd | Health & social care | 2025 |
| Bora Group Limited | Real estate | 2026 |
| Bored on Business Limited | Information & communication | 2018 |
| Borr Properties Ltd | Real estate | 2024 |
| Borste Ltd | Real estate | 2024 |
| Bossmen International Limited | Wholesale & retail | 2024 |
| Bostrix Care and Education Ltd | Administrative & support | 2023 |
| Botanica BPC 1 Limited | Health & social care | 2026 |
| Botch Limited | Health & social care | 2014 |
| Botha Property Management Limited | Administrative & support | 2009 |
| Bottle & Basket Ltd | Wholesale & retail | 2024 |
| Bottle Hub Limited | Wholesale & retail | 2026 |
| Botwell Common Ltd | Real estate | 2017 |
| Botwell Limited | Real estate | 2021 |
| Botánica Products Ltd | Other services | 2016 |
| Bougainvillea Properties Ltd | Real estate | 2025 |
| Boumendil Property Holdings Ltd | Real estate | 2026 |
| Bouncy Party UK Ltd | Arts & recreation | 2020 |
| Bourne END Homes Ltd | Real estate | 2025 |
| Bouzigues Developments Limited | Administrative & support | 2003 |
| Bowbanks EM Services Limited | Professional & scientific | 2012 |
| Bower Way Development Limited | Real estate | 2025 |
| Bowleys Building Services Ltd | Construction | 2025 |
| Bowlz Ltd | Wholesale & retail | 2025 |
| Bowtique Events Ltd | Manufacturing | 2020 |
| Box of Beauty Ltd | Wholesale & retail | 2019 |
| Boxnest Ltd | Wholesale & retail | 2025 |
| Boxverge Ltd | Wholesale & retail | 2025 |
| Boyack Enterprises Limited | Health & social care | 2001 |
| Boyndon Road Residents Limited | Households | 1988 |
| BP Nextgen Ltd | Real estate | 2025 |
| BPF Cars Limited | Transport & logistics | 2022 |
| BPG Dasari Limited | Information & communication | 2015 |
| Bpra Limited | Professional & scientific | 2007 |
| BPV Servicing LLP | | 2024 |
| BR Builders Services Ltd | Construction | 2023 |
| Bradley Walsh Data Consultancy Ltd | Information & communication | 2024 |
| Braham Construction Limited | Construction | 2021 |
| Braham Glazing Ltd | Manufacturing | 2019 |
| Brahamdoors Ltd | Construction | 2024 |
| Brahm Glazing Ltd | Construction | 2025 |
| Braidsapp Limited | Information & communication | 2020 |