| Baaad Kitty Limited | Information & communication | 2019 |
| Baack Software Ltd | Information & communication | 2025 |
| Babis Koffas Limited | Professional & scientific | 2006 |
| Babyen Limited | Information & communication | 2012 |
| Back of House Events Limited | Professional & scientific | 2026 |
| Backed - Thought Machine 1 LLP | | 2021 |
| Backfoot Technologies Ltd | Information & communication | 2023 |
| Badlow Properties IX Limited | Real estate | 1997 |
| Badlow Properties V Limited | Real estate | 1992 |
| Badlow Properties VI Limited | Real estate | 1992 |
| Badlow Properties Viii Limited | Real estate | 1992 |
| Badri International Ltd | Health & social care | 2016 |
| Bagnall & Woodward Electrical Contractors Limited | Construction | 2017 |
| Bags and Baggage Ltd | Wholesale & retail | 2025 |
| Bailey General Contracting Ltd | Information & communication | 2012 |
| Bailey Smith Consulting Limited | Construction | 2015 |
| Bailey-Arnold Limited | Other services | 2017 |
| Baily Group Ltd | Construction | 2017 |
| Baipothaimassage Limited | Health & social care | 2019 |
| Balanced Education Limited | Education | 2020 |
| Balanced Outsourcing Ltd | Professional & scientific | 2021 |
| Balham Butchers Limited | Wholesale & retail | 2019 |
| Ballard Loft Rooms Ltd | Construction | 2018 |
| Balmoral Advisory Services Limited | Administrative & support | 2020 |
| Balmoral Global Capital Limited | Financial services | 2017 |
| Baloun Enterprises Limited | Wholesale & retail | 2008 |
| Bambino Bloom Limited | Wholesale & retail | 2015 |
| Bamzyk Limited | Education | 2010 |
| Bandicoot Studios Ltd | Information & communication | 2021 |
| Bandino Limited | Wholesale & retail | 2011 |
| Banna Equestrian Limited | Agriculture & fishing | 2023 |
| Bannister Consultants Limited | Professional & scientific | 2010 |
| Bantry Properties Limited | Construction | 1986 |
| Baobab Land Limited | Construction | 2017 |
| Bardar Services Ltd | Construction | 2018 |
| Barden Properties Limited | Real estate | 2023 |
| Bardwell Roofing Ltd | Construction | 2025 |
| Baresta UK Ltd | Hospitality | 2016 |
| Barfi Bites Ltd | Wholesale & retail | 2023 |
| Barka Construction Limited | Construction | 2008 |
| Barka Property Management Limited | Real estate | 2012 |
| Barkston Gardens (EC) Limited | Real estate | 2023 |
| Barkwell Ventures Limited | Information & communication | 2025 |
| Barnes & Jones Creative Limited | Professional & scientific | 2026 |
| Barnsbury Joinery Co Limited | Construction | 2018 |
| Barot Financial Services Ltd | Professional & scientific | 2015 |
| Barretts Industries Ltd | Manufacturing | 2007 |
| Barrie Johnston Limited | Health & social care | 2013 |
| Barry the Cactus Limited | Wholesale & retail | 2017 |
| Bars and Tone Engineering Limited | Professional & scientific | 2026 |
| Baruch T Ltd | Wholesale & retail | 2023 |
| Baseline Outreach CIC | Health & social care | 2025 |
| Basic Livings Limited | Real estate | 2020 |
| Basildon View Cottage (RR) Limited | Real estate | 2022 |
| Basis Cosec Limited | Professional & scientific | 2016 |
| Bass JAM Ltd | Real estate | 2019 |
| Batch Wood Akshran Ltd | Wholesale & retail | 2018 |
| Batchfields Investments Limited | Financial services | 2022 |
| Battlekart ST Albans Ltd | Arts & recreation | 2023 |
| Battlers Investments Limited | Financial services | 2019 |
| BAU Fire & Security Limited | Construction | 2022 |
| BAU Plants Ltd | Wholesale & retail | 2022 |
| Bauk Community Interest Company | Health & social care | 2024 |
| Baulsh Bespokes Limited | Manufacturing | 2024 |
| BBE Holdings Limited | Financial services | 2017 |
| BC & MC (UK) Limited | Professional & scientific | 2021 |
| BC Construction Ltd | Construction | 2023 |
| BC Tax Filing Ltd | Information & communication | 2016 |
| BCG Auto Ltd | Wholesale & retail | 2017 |
| Bddo Consultants Ltd | Wholesale & retail | 2021 |
| BDS Sets Ltd | Information & communication | 2011 |
| BE (ST Albans) Limited | Wholesale & retail | 2014 |
| BE Media Ltd | Information & communication | 2014 |
| Beacon House ST Albans RTM Company Limited | Households | 2024 |
| Beaconsfield Road (ST. Albans) Management Company Limited | Households | 1987 |
| Beales Electrical Contracting Services Ltd | Construction | 2004 |
| Bean to Barrel Ltd | Hospitality | 2024 |
| Beanie and Beard Ltd | Information & communication | 2025 |
| Bearcroft People & Change Ltd | Administrative & support | 2026 |
| Beard & Co HG Ltd | Other services | 2025 |
| Beare & SON Limited | Wholesale & retail | 2002 |
| Beast Kestrel SPV I LLP | | 2021 |
| Beat Concepts Holdings Limited | Financial services | 2017 |
| Beatbike Studios Ltd | Arts & recreation | 2012 |
| Beaumont Berry Consulting Limited | Agriculture & fishing | 2024 |
| Beaumont Brass Band Ltd | Wholesale & retail | 2026 |
| Beaumont Hall Limited | Hospitality | 2019 |
| Beaumont School | Education | 2012 |
| Beauteous Beauty & Aesthetics Ltd | Other services | 2025 |
| Beauty Butterfly Ltd | Professional & scientific | 2019 |
| Beauty by Ariana Ltd | Other services | 2024 |
| Beauty R US Limited | Wholesale & retail | 2018 |
| Becky Allard Ltd | Professional & scientific | 2016 |
| Become Interiors Limited | Professional & scientific | 2018 |
| BED of Roses Advertising Limited | Administrative & support | 2009 |
| Bedford Assets NO1 Ltd | Real estate | 2015 |
| Bedford Hill Limited | Households | 2007 |
| Bedfordshire Logs Limited | Arts & recreation | 2012 |
| BEE Advised Ltd | Information & communication | 2019 |
| BEE Creative Ltd | Professional & scientific | 2018 |