| BMT Properties Limited | Real estate | 2019 |
| BNF Transport Ltd | Transport & logistics | 2026 |
| BNG Global T&E Limited | Professional & scientific | 2025 |
| BNK Care Ltd | Health & social care | 2018 |
| BNK Evolution Ltd | Health & social care | 2023 |
| BNS Building Solutions Ltd | Construction | 2024 |
| Boast Education Limited | Hospitality | 2015 |
| Boatwrecks.Com Limited | Professional & scientific | 2000 |
| BOB UK Builders Limited | Construction | 2026 |
| Bobag Ltd | Health & social care | 2024 |
| Bobtails Ltd | Real estate | 1998 |
| Bodo Construct Ltd | Construction | 2019 |
| Body Active Health and Fitness Ltd | Arts & recreation | 2009 |
| Bogacz Limited | Wholesale & retail | 2016 |
| Bogap Medical Limited | Health & social care | 2023 |
| Bohemialove Ltd | Wholesale & retail | 2024 |
| Boilr Ltd | Construction | 2020 |
| Bojja Limited | Health & social care | 2021 |
| Bolade Property Services Ltd | Real estate | 2021 |
| Bolamark Engineering UK Ltd | Construction | 2022 |
| Bolaric Limited | Information & communication | 2021 |
| Bolbol Imports Ltd | Manufacturing | 2019 |
| Bold Brand Media Ltd | Manufacturing | 2025 |
| Boldesign Limited | Professional & scientific | 2018 |
| Bolt ‘N’ Go Limited | Manufacturing | 2024 |
| Bolton Nigerian Muslim Community | Health & social care | 2024 |
| Bonavyl Ltd | Health & social care | 2024 |
| Bond Place (Management Company) Limited | Households | 2002 |
| Boni & Partners Ltd | Health & social care | 2024 |
| Bonito Grill Ltd | Hospitality | 2024 |
| Bonjoe Ltd | Information & communication | 2025 |
| Bonner Developers Limited | Information & communication | 2025 |
| Bonnington Yard Management Company Ltd | Real estate | 2025 |
| Bookmans Yard Management Company Limited | Households | 2001 |
| Bookzy Ltd | Wholesale & retail | 2024 |
| Boon Afro-Caribbean Hair Lounge Ltd | Wholesale & retail | 2025 |
| Boost Your a Levels Limited | Education | 2023 |
| Booths and Bots Limited | Arts & recreation | 2021 |
| Boots in Nature Ltd | Education | 2025 |
| Boran Properties Ltd | Other services | 2017 |
| BOS Projects Consultancy Limited | Professional & scientific | 2015 |
| Bosh Ltd | Administrative & support | 2024 |
| Bosjof Ltd | Public administration | 2023 |
| Boss Beaus Bargains Ltd | Wholesale & retail | 2024 |
| Botech UK Ltd | Information & communication | 2020 |
| Botezatu Electrical Ltd | Construction | 2026 |
| Bounce BED Bishops Stortford Limited | Administrative & support | 2025 |
| Bouncefitbody Ltd | Other services | 2015 |
| Boundary House (Kings Road) Limited | Households | 2013 |
| Bourne & Co Property Management Limited | Real estate | 2025 |
| Bourne Property Maintenance Limited | Administrative & support | 2007 |
| BOW Arrow Management Company Limited | Households | 1989 |
| BOW Farm Management Company Limited | Households | 2016 |
| Bowlby Hill (ST. Georges House) Limited | Households | 2023 |
| Bowlers Croft Hadleigh (Management Company) Limited | Households | 2025 |
| Bowood Gate Management Company Limited | Households | 2018 |
| Box Legal Lending Limited | Financial services | 2022 |
| Box Legal Limited | Financial services | 2003 |
| Bozol Business Solution Ltd | Information & communication | 2018 |
| BP Plumbing Ltd | Construction | 2024 |
| BP3 Consult Ltd | Wholesale & retail | 2024 |
| Bpes London Ltd | Construction | 2019 |
| BPL Groundworker Limited | Construction | 2019 |
| BPS Solutions Limited | Other services | 2003 |
| Braam Truter Civil Engineers Limited | Construction | 2007 |
| Brackendale Management Company Limited | Households | 1988 |
| Bradley Consultancy Services Ltd | Construction | 2024 |
| Braggdoc Ltd | Health & social care | 2023 |
| Braide Consultancy Services Limited | Health & social care | 2015 |
| Braide Consulting Limited | Information & communication | 2014 |
| Braims Ltd | Administrative & support | 2024 |
| Braintree Glass Ltd | Construction | 2023 |
| Bramble Court (Acorn House) Ltd | Households | 2012 |
| Bramble Court (Cedar House) RTM Company Ltd | Households | 2012 |
| Bramble Court (Thistle House) RTM Company Limited | Households | 2012 |
| Bramble Crescent Ltd | Health & social care | 2026 |
| Bramtrans Ltd | Transport & logistics | 2023 |
| Branch Solutions Limited | Administrative & support | 2022 |
| Brandthrive UK Ltd | Professional & scientific | 2025 |
| Brandvector Creative Ltd | Professional & scientific | 2025 |
| BRB Property Solutions Ltd | Hospitality | 2016 |
| Breakfast Briefing Ltd | Professional & scientific | 2020 |
| Breakwells Legal Limited | Professional & scientific | 2022 |
| Brew Dynamics Ltd | Manufacturing | 2012 |
| Brick Lane E1 Ltd | Financial services | 2023 |
| Bricketts Way (Newport) Management Company Ltd | Households | 2022 |
| Bridford Bespoke Solutions Ltd | Financial services | 2012 |
| Bridge Cottage Services (NO.1) Ltd | Real estate | 2015 |
| Bridge Park Gymnastics Club Limited | Arts & recreation | 2018 |
| Bridgeway Health Limited | Health & social care | 2026 |
| Bridletree Limited | Construction | 2011 |
| Brieley Hill Investments Limited | Construction | 2005 |
| Bright Beginnings Ltd | Other services | 2012 |
| Bright Electrical Solutions Ltd | Construction | 2024 |
| Bright Gray Studio Limited | Professional & scientific | 2015 |
| Bright Hygiene Management (London) Limited | Other services | 1990 |
| Bright Security Services Ltd | Administrative & support | 2025 |
| Brighter Building Group Ltd | Real estate | 2025 |
| Brighter Bunning Way Limited | Households | 1989 |
| Brighter Bunning Way RTM Company Ltd | Households | 2012 |