| Blaclane Ltd | Real estate | 2016 |
| Bladon Lodge Residents Company Limited | Households | 1996 |
| Blak Lite Design Limited | Administrative & support | 2017 |
| Bland People Limited | Administrative & support | 2013 |
| BLC Electrical Services Ltd | Construction | 2021 |
| Block Toyz Limited | Wholesale & retail | 2025 |
| Bloom and Bird Ltd | Wholesale & retail | 2022 |
| Bloom Collective Ltd | Hospitality | 2022 |
| Blossom Business Limited | Wholesale & retail | 2020 |
| Blossom Grove (Retford) Limited | Construction | 2014 |
| Blossom Prop Ltd | Real estate | 2021 |
| Blossoms Investments (UK) Ltd | Real estate | 2019 |
| BLU DOT Limited | Real estate | 2024 |
| Blue Arch Construction Ltd | Construction | 2021 |
| Blue Bricks Group Ltd | Construction | 2016 |
| Blue Bricks Investment Limited | Real estate | 2021 |
| Blue Castor Limited | Other services | 2017 |
| Blue Door 54 Limited | Administrative & support | 2015 |
| Blue Fern Ltd | Professional & scientific | 2019 |
| Blue Lily Home Care Limited | Health & social care | 2018 |
| Blue Mahoe Ltd | Households | 2024 |
| Blue Mortar Ltd | Real estate | 2021 |
| Blue Motus Ltd | Manufacturing | 2024 |
| Blue Nurseries Limited | Agriculture & fishing | 2011 |
| Blue Sapphire Support Services Ltd | Administrative & support | 2012 |
| Blue Sky IT Consultants Ltd | Information & communication | 2013 |
| Blue Sky OD Ltd | Other services | 2025 |
| Blue Spectrum Services Ltd | Professional & scientific | 2023 |
| Blue Star Glazing Limited | Manufacturing | 2021 |
| Blue Suede (UK) Limited | Other services | 2002 |
| Bluebell Vineyard Estates Limited | Manufacturing | 1982 |
| Bluefire Investments Ltd | Real estate | 2022 |
| Bluemoor Properties Ltd | Real estate | 2010 |
| Bluepedal Limited | Real estate | 2006 |
| Blueshades International Ltd | Construction | 2023 |
| Blueskyports Ltd | Wholesale & retail | 2024 |
| Bluestag Coaching Ltd | Professional & scientific | 2012 |
| Bluestag Leadership Limited | Professional & scientific | 2020 |
| Bluetec Technical Services Ltd | Construction | 2026 |
| BM Accommodation Ltd | Real estate | 2022 |
| BMC Fitout Limited | Construction | 2021 |
| Bmec Partners LP | | 2023 |
| BMX Sponsorship Ltd | Arts & recreation | 2025 |
| BN London Ltd | Wholesale & retail | 2022 |
| BN Partners LLP | | 2021 |
| BNK Accountants Ltd | Professional & scientific | 2013 |
| BNM Healthcare Ltd | Health & social care | 2022 |
| Bnova Ltd | Hospitality | 2015 |
| Bobby Barber London Ltd | Other services | 2024 |
| Bodymatters Clinic Ltd | Health & social care | 2011 |
| Bodywise Properties Limited | Real estate | 2021 |
| Boeme World Ltd | Wholesale & retail | 2024 |
| Bogdan Construct Limited | Construction | 2019 |
| Bogjisha Ltd | Hospitality | 2018 |
| Bogjisha Properties Ltd | Real estate | 2025 |
| Boiler Breakdowns London Ltd | Extraterritorial | 2022 |
| Boiler Care Club Ltd | Construction | 2020 |
| Boiler Hero Ltd | Construction | 2015 |
| Boiler Heroes Ltd | Construction | 2013 |
| Bollywood Dance Entertainment Ltd | Arts & recreation | 2026 |
| Bollywood Dance School Limited | Education | 2026 |
| Bollywood Dance School London Limited | Education | 2026 |
| Boltprep Ltd | Information & communication | 2017 |
| Bolus Ltd | Information & communication | 2026 |
| BON Accord Advisory Limited | Professional & scientific | 2025 |
| Bonjour French Ltd | Information & communication | 2026 |
| Bonusdate Limited | Wholesale & retail | 1990 |
| Bonza TV Limited | Information & communication | 2002 |
| Bookbinder TW Limited | Real estate | 2025 |
| Boreality Ltd | Professional & scientific | 2024 |
| Borough & Peak Limited | Hospitality | 2026 |
| Borough 33 Ltd | Wholesale & retail | 2022 |
| Boston Tasty Ltd | Wholesale & retail | 2019 |
| Bottomline Ventures Ltd | Professional & scientific | 2024 |
| Boundary Road Limited | Real estate | 2010 |
| Bounds Green Health and Fitness Ltd | Health & social care | 2022 |
| BP QA Consulting Limited | Information & communication | 2016 |
| BPE Investments Limited | Real estate | 2025 |
| BPE Solutions Limited | Administrative & support | 2026 |
| Bprompt Ltd | Information & communication | 2024 |
| BPS Care Limited | Real estate | 2020 |
| BR Architects Ltd | Professional & scientific | 2024 |
| BR Electrical Services Ltd | Other services | 2014 |
| Bradcode Limited | Real estate | 1992 |
| Bradley & Jones Limited | Other services | 2022 |
| Bradley-Hole Schoenaich Landscape Architects Limited | Professional & scientific | 2010 |
| Bradonview Properties Limited | Real estate | 1989 |
| Brake Conference Limited | Administrative & support | 2015 |
| Brampton Group Developments Limited | Construction | 2020 |
| Bramstone Atthill Ltd | Real estate | 2019 |
| Brealy Management Company (NO.2) Limited | Households | 1986 |
| Breez Motors Ltd | Wholesale & retail | 2025 |
| Brema 36 Pro Ltd | Construction | 2024 |
| Brennah Limited | Professional & scientific | 2014 |
| Brewers Blend Ltd | Manufacturing | 2023 |
| Brian COX & Company (North Harrow) Limited | Real estate | 2016 |
| Bricks & Mortar Designs Ltd | Construction | 2023 |
| Bricks & Mortar Enterprises Ltd | Construction | 2011 |
| Bricks & Mortar Homes Limited | Real estate | 2018 |
| Bridal Trunk by Divya Limited | Wholesale & retail | 2020 |