| BMC Commercial Events Limited | Arts & recreation | 2026 |
| BMV Guys Limited | Administrative & support | 2020 |
| BNR Global Supply Group Ltd | Wholesale & retail | 2020 |
| Board-Worx Limited | Professional & scientific | 2009 |
| BOB and BEE Creative Limited | Professional & scientific | 2012 |
| BOB Consulting Limited | Professional & scientific | 2014 |
| Boba Magic Ltd | Hospitality | 2025 |
| Boba Tree Limited | Hospitality | 2022 |
| Bobatime Ltd | Hospitality | 2024 |
| Bobbys Bar 2021 Limited | Hospitality | 2021 |
| Bodewell Living Ltd | Real estate | 2025 |
| Body Glow Ltd | Other services | 2020 |
| Bodyglow Tanning Solutions Limited | Other services | 2022 |
| Bohemian Vapecity Ltd | Wholesale & retail | 2017 |
| Bolanle Idris Aremu Limited | Professional & scientific | 2016 |
| Bonafide Property Investors Company Ltd | Real estate | 2023 |
| Bondcote (Medway) Limited | Construction | 2001 |
| Bonnierae Services Limited | Real estate | 2022 |
| Bonsall Consulting Limited | Professional & scientific | 2023 |
| BOO and the Bear Ltd | Manufacturing | 2023 |
| BOO LA Soaps and Candles Ltd | Wholesale & retail | 2025 |
| Bookacourse Ltd | Education | 2019 |
| Bookranger Limited | Wholesale & retail | 2023 |
| Books & Balance Ltd | Professional & scientific | 2023 |
| Bookscape Books Limited | Wholesale & retail | 2026 |
| Boosta Vape and Shisha Ltd | Wholesale & retail | 2025 |
| Boot Camp Stores Limited | Wholesale & retail | 2019 |
| Boran Kent Limited | Wholesale & retail | 2025 |
| Born to WIN Jackpot Ltd | Arts & recreation | 2026 |
| Borough Playground Inspections Ltd | Professional & scientific | 2023 |
| Boroughs Property Ltd | Real estate | 2024 |
| Bosh Talent Group Limited | Professional & scientific | 2018 |
| Botchey Medical Ltd | Health & social care | 2019 |
| Botnics Ltd | Manufacturing | 2023 |
| Boubou Boutique Limited | Wholesale & retail | 2023 |
| Bougourd Psychology Limited | Education | 2025 |
| Bouncebackability Ltd | Health & social care | 2026 |
| Boundary Line Property Ltd | Real estate | 2021 |
| Bourn Transport Logistics Ltd | Transport & logistics | 2020 |
| Bournville Building Company Ltd | Construction | 2006 |
| Boutique Bathroom Fitters Ltd | Construction | 2022 |
| BOW Financial Services Limited | Financial services | 2019 |
| Bowen Group Ltd | Wholesale & retail | 2024 |
| Bowes Homes Ltd | Real estate | 2023 |
| Bowoodlery Limited | Wholesale & retail | 2024 |
| Box City Limited | Transport & logistics | 2019 |
| Box City Sunderland Quay Limited | Administrative & support | 2022 |
| Box Experts Ltd | Transport & logistics | 2021 |
| Boxall MEP Ltd | Professional & scientific | 2017 |
| Boykov Ltd | Construction | 2017 |
| BOYKOV93 Ltd | Transport & logistics | 2017 |
| BP Offshore Ltd | Energy | 2022 |
| BR Electric Ltd | Construction | 2015 |
| Bradelec Building Services Ltd | Construction | 2019 |
| Bradford Student Homes Limited | Hospitality | 2025 |
| Braemar, Brook & New Limited | Professional & scientific | 2018 |
| Brajan Ltd | Wholesale & retail | 2022 |
| Bramblelodge (Sittingbourne) Limited | Real estate | 1996 |
| Brand Cakes & Chocolates Ltd | Hospitality | 2025 |
| Brand Strategies Limited | Information & communication | 2019 |
| Brandify Technologies Limited | Information & communication | 2022 |
| Brav Limited | Construction | 2010 |
| Brave Women International | Other services | 2025 |
| Bravo UK Removals Limited | Other services | 2014 |
| Bravotile Ltd | Construction | 2014 |
| Brawl Sports Ltd | Wholesale & retail | 2026 |
| Brayen Cleaning Services Ltd | Administrative & support | 2024 |
| BRC Holding Group Limited | Financial services | 2023 |
| Brebson & Son's Ltd | Wholesale & retail | 2016 |
| Bredhurst Bathrooms Ltd | Other services | 2004 |
| Brentfield Consultancy Ltd | Professional & scientific | 1999 |
| Brenton Holdings Limited | Real estate | 2020 |
| Bricks Capital (UK) Ltd | Professional & scientific | 2010 |
| Bricks Capital Holdings 2 Limited | Financial services | 2022 |
| Bricks K4 Capital Limited | Professional & scientific | 2014 |
| Bricks Silverstone Capital Limited | Financial services | 2018 |
| Bricktek Limited | Construction | 2008 |
| Bridgepointglobalholding Ltd | Financial services | 2026 |
| Bridges Electrical Engineering Services Limited | Professional & scientific | 2016 |
| Bridgeside Wharf Limited | Real estate | 2022 |
| Bridgewater Properties Group Ltd | Real estate | 2026 |
| Bridgewood Asset Managers Limited | Real estate | 2021 |
| Bridging Worlds Consulting Limited | Professional & scientific | 2020 |
| Bright Brains Global Limited | Administrative & support | 2018 |
| Bright Managements Group Limited | Arts & recreation | 2024 |
| Bright Signage UK Ltd | Information & communication | 2021 |
| Brighter City Solutions Limited | Professional & scientific | 2018 |
| Brighton Homes Limited | Real estate | 2009 |
| Brightstep Lile Ltd | Other services | 2023 |
| Brimsted Autos Ltd | Wholesale & retail | 2023 |
| Brimstone Global Ltd | Public administration | 2019 |
| Brimstone Mosaic Ltd | Financial services | 2020 |
| Brimstone Site Investigation Ltd | Public administration | 2016 |
| Bring Every Kind Smile (Beks) Community Interest Company | Arts & recreation | 2020 |
| Briswick Heating Ltd | Construction | 2018 |
| Britannia Employment & Estate Management Limited | Real estate | 2021 |
| Britannia Fire Solutions Ltd | Construction | 2022 |
| Brite Build Limited | Construction | 2020 |
| British Milers' Club Limited | Arts & recreation | 2005 |
| Britmed Healthcare Ltd | Health & social care | 2017 |