| Blue Heron Consultancy Limited | Information & communication | 2016 |
| Blue Horizon Solutions (HR) Ltd. | Professional & scientific | 2015 |
| Blue River Controls Limited | Manufacturing | 2003 |
| Blue Robin Group Limited | Wholesale & retail | 2023 |
| Blue Skies Garden Services Limited | Other services | 2013 |
| Blue Sky Delta Limited | Real estate | 2021 |
| Blue Sky Venues Limited | Administrative & support | 2007 |
| Blue Strike Consulting Limited | Professional & scientific | 2025 |
| Blue Vision Consulting Ltd | Information & communication | 2009 |
| Bluejays Infotech Limited | Information & communication | 2022 |
| Bluejeyproductions Limited | Information & communication | 2023 |
| Bluemoon Executive Limited | Transport & logistics | 2025 |
| Bluesky AB Cleaning Ltd | Administrative & support | 2024 |
| Bluesky BA Cleaning Ltd | Administrative & support | 2024 |
| Bm&Nco Ltd | Manufacturing | 2017 |
| Bmbix Operations (UK) Ltd | Information & communication | 2014 |
| BMC Yarmouth Limited | Construction | 2019 |
| BMD Freight Transport Ltd | Transport & logistics | 2021 |
| BMM Property Management Ltd | Real estate | 2018 |
| BMS Production Finance Limited | Information & communication | 2026 |
| Boardgame Changer Ltd | Manufacturing | 2025 |
| Boars Hill Farm Limited | Agriculture & fishing | 2012 |
| Bochkoltz & Associates Ltd | Health & social care | 2022 |
| Body Connection Limited | Other services | 2005 |
| Body&San Ltd | Manufacturing | 2016 |
| BOE & Murphy Limited | Hospitality | 2024 |
| Boffins (Thames Valley) Ltd | Information & communication | 2012 |
| Bokov Ltd | Real estate | 2023 |
| Bola UK Entreprises Limited | Transport & logistics | 2014 |
| Bold Sports Ltd | Wholesale & retail | 2025 |
| Boldcube Ltd | Wholesale & retail | 2017 |
| Boldwyse Limited | Information & communication | 2022 |
| Boliz Professionals Ltd | Wholesale & retail | 2023 |
| BOM Bites Ltd | Hospitality | 2026 |
| Bombay Wala Ltd | Manufacturing | 2020 |
| Bonavista Group Limited | Households | 2019 |
| Bonbon Hospitality Ltd | Hospitality | 2022 |
| Booboozainy Ltd | Real estate | 2023 |
| Bookasana Ltd | Information & communication | 2025 |
| Booker Cabs | | 1992 |
| Booker Coaches Limited | Transport & logistics | 2002 |
| Bookies Investments Ltd | Financial services | 2025 |
| Bookkeepers Summit Limited | Education | 2016 |
| Boost Them ALL Limited | Wholesale & retail | 2026 |
| Boostora Ltd | Professional & scientific | 2026 |
| Boot Academy Limited | Education | 2023 |
| Booth Apex Munitions Ltd | Manufacturing | 2025 |
| Borne Fitness Ltd | Arts & recreation | 2024 |
| Bose Accountancy Ltd | Professional & scientific | 2016 |
| Boss Kebabz Ltd | Hospitality | 2026 |
| Boss Your Numbers Ltd | Education | 2024 |
| Bosunmere Limited | Professional & scientific | 1927 |
| Bothas Connections Ltd | Information & communication | 2023 |
| Botifytech Ltd | Professional & scientific | 2024 |
| Boughton Properties Limited | Real estate | 1958 |
| Boundless Possibilities Limited | Professional & scientific | 2019 |
| Bourn Productions Ltd | Arts & recreation | 2023 |
| Bourne END Parade Taxis Ltd | Transport & logistics | 2018 |
| Bourne for Fitness Ltd | Arts & recreation | 2009 |
| BOW TIE Construction Ltd | Construction | 2011 |
| Bowlscrown Limited | Professional & scientific | 1978 |
| Bowyer and Davis Limited | Construction | 1959 |
| Boyce Business Equipment Limited | Wholesale & retail | 1978 |
| Bozkurt Barbers Ltd | Other services | 2023 |
| BP Bennett & SON Roofing Limited | Construction | 2025 |
| Bpam Properties Limited | Real estate | 2024 |
| Bprolife Ltd | Real estate | 2024 |
| BPS Roofing Services Limited | Construction | 2014 |
| BPV Ventures Limited | Hospitality | 2024 |
| Bradar 1 Limited | Information & communication | 2016 |
| Bradar 2 Limited | Information & communication | 2016 |
| Bradbury Tracks Limited | Wholesale & retail | 1997 |
| Bradenham Development Ltd | Financial services | 2024 |
| Bradley Evolve Limited | Construction | 2026 |
| Braemar Sales Ltd | Construction | 2018 |
| Braidford Accountancy Services Limited | Professional & scientific | 2000 |
| Brainshop Limited | Professional & scientific | 2010 |
| Brainwaves Books Limited | Information & communication | 1998 |
| Brambles and Botanicals Limited | Wholesale & retail | 2025 |
| Bramley Park Management Company Limited | Households | 2023 |
| Brand Centric Network Limited | Professional & scientific | 2005 |
| Brand Online Limited | Wholesale & retail | 2022 |
| Branding Focus Limited | Administrative & support | 2014 |
| Brantham Residential Estate Management Company Limited | Extraterritorial | 2020 |
| Brass Bathtub CIC | Education | 2019 |
| Brave Innovations Ltd | Information & communication | 2017 |
| Brazenor's Brews Ltd | Manufacturing | 2023 |
| Breakdown Breakdown Limited | Wholesale & retail | 2016 |
| Breakthrough Education Learning C.I.C. | Education | 2024 |
| Brec Electrical Ltd. | Construction | 2015 |
| Breezefree Limited | Administrative & support | 2000 |
| Breffni Properties Ltd | Real estate | 2012 |
| Brenamore Consultants Ltd | Administrative & support | 2025 |
| Brentford Coaches Limited | Transport & logistics | 2003 |
| Briaily Architects Ltd | Professional & scientific | 2019 |
| Brick PR Ltd. | Information & communication | 2013 |
| Bricksy Properties Ltd | Real estate | 2025 |
| Bricktown Ltd | Construction | 2008 |
| Bridge Anaesthetic Services Ltd | Health & social care | 2026 |
| Bridge House 183 Gordon Road Limited | Households | 2005 |