| Barview Limited | Administrative & support | 1999 |
| Basingstoke Packaging Limited | Manufacturing | 1979 |
| Bassett Close Limited | Construction | 2021 |
| BAT Barbers Limited | Other services | 2019 |
| Bctpm Limited | Professional & scientific | 2013 |
| BE Inspired Designs Ltd | Professional & scientific | 2014 |
| Beam Global Distribution Consultancy Ltd | Professional & scientific | 2026 |
| Beautiful Angels Ltd | Other services | 2009 |
| Beautiful Angels Wellbeing Limited | Other services | 2013 |
| Beauwest Properties Limited | Construction | 2000 |
| Bebright Ltd | Information & communication | 2025 |
| BEE Consulting & Coaching Ltd | Professional & scientific | 2022 |
| BEE Smart Consulting Ltd | Professional & scientific | 2019 |
| Beechwood Consultancy Limited | Administrative & support | 2006 |
| Belay Limited | Information & communication | 2017 |
| Bell Street One Limited | Construction | 2026 |
| Bella Cucina Ltd | Hospitality | 2025 |
| Ben's Berkshire Bees Limited | Agriculture & fishing | 2018 |
| Berkshire Cleaning Solutions Ltd | Administrative & support | 2024 |
| Berkshire Commercials Ltd | Wholesale & retail | 2017 |
| Berkshire Construction Limited | Other services | 2013 |
| Berkshire Event Catering Limited | Hospitality | 2012 |
| Berkshire Garden Buildings Limited | Wholesale & retail | 2005 |
| Berkshire Health & Well-Being Social Enterprises | Health & social care | 2009 |
| Berkshire Kitchens & Bathrooms Ltd | Administrative & support | 2017 |
| Berkshire Ophthalmic Laboratories Limited | Manufacturing | 1952 |
| Berkshire Weight Lifting Ltd | Other services | 2017 |
| Berongrange Limited | Real estate | 1999 |
| Berry Brook Developments Limited | Construction | 2017 |
| Bespoke Stonework Ltd | Administrative & support | 2008 |
| Bextravagant Limited | Other services | 2015 |
| Bidquest Limited | Professional & scientific | 2025 |
| Biggs Property Holdings Ltd | Real estate | 2023 |
| Biker Meetups Ltd | Information & communication | 2026 |
| Bimb Music Ltd | Arts & recreation | 2025 |
| Binary Marketing Ltd | Information & communication | 2025 |
| Bioscience Writing Limited | Professional & scientific | 2025 |
| Bishop Legal Consulting Services Ltd | Professional & scientific | 2023 |
| Bishopton Estates Ltd | Real estate | 2002 |
| Biss Project Management Ltd | Professional & scientific | 2020 |
| BJE Photography Limited | Professional & scientific | 2015 |
| BJT Enterprises Ltd | Wholesale & retail | 2026 |
| BK Firefly Designs Ltd | Arts & recreation | 2026 |
| Black Chilli Marketing Limited | Administrative & support | 2013 |
| Black Cygnet (Hungerford) Limited | Real estate | 2025 |
| Black Cygnet Holdings Limited | Real estate | 2025 |
| Black Cygnet Lettings Limited | Real estate | 2019 |
| Black Cygnet Properties Limited | Real estate | 2017 |
| Black Palm Audio Ltd | Information & communication | 2026 |
| Blackrock Roofing & Developments Ltd. | Construction | 2024 |
| Blamco Property Ltd | Real estate | 2023 |
| Blendin Ltd | Professional & scientific | 2021 |
| Blink Estate Services Limited | Professional & scientific | 2014 |
| Blue Beetle Ceramics Ltd | Arts & recreation | 2019 |
| Blue DOT Energy & Environment Limited | Professional & scientific | 2026 |
| Blue Monkey Services Limited | Information & communication | 2018 |
| Bmsr Ltd | Construction | 2021 |
| BOA Consulting Limited | Professional & scientific | 2011 |
| BOA FP Systems Limited | Information & communication | 1999 |
| Boar Construction UK Limited | Construction | 2026 |
| Boarswood Holdings Limited | Financial services | 2025 |
| Boarswood Properties Limited | Real estate | 2024 |
| BOL Holdings Limited | Professional & scientific | 2005 |
| Bookai Consultancy Ltd | Professional & scientific | 2023 |
| Boski London Limited | Wholesale & retail | 2023 |
| Boundary Road Garage (Newbury) Ltd | Wholesale & retail | 2015 |
| BOW Brook Management Company Limited | Households | 2023 |
| Boyles Plumbing and Heating Ltd | Construction | 2022 |
| BP Fitness Limited | Extraterritorial | 2022 |
| BPS Leisure Limited | Manufacturing | 1996 |
| Brabazons Garden Maintenance Limited | Administrative & support | 2017 |
| Brackley 2A Ltd | Real estate | 2020 |
| Breadmore Commercials Limited | Wholesale & retail | 2003 |
| Breaking Barriers Theatre Classes LLP | | 2024 |
| Breathe Pictures Limited | Professional & scientific | 2010 |
| Breithorn Engineering Limited | Administrative & support | 2008 |
| Brew Crew Coffee Limited | Manufacturing | 2021 |
| Brickell Swimming Pools Limited | Construction | 1963 |
| Brickwall Technologies Limited | Information & communication | 2023 |
| Bridge-It Options Ltd | Administrative & support | 2014 |
| Brightstay Properties Ltd | Real estate | 2025 |
| Brimstone Living 7 Limited | Real estate | 2024 |
| Brindabella Ventures Limited | Professional & scientific | 2024 |
| Brit Care Solutions Ltd. | Health & social care | 2020 |
| British Estate Services (Properties) Limited | Manufacturing | 1947 |
| British Estate Services Limited | Construction | 1934 |
| Britton & Machin Limited | Real estate | 2022 |
| Broad Speed Automotive Ltd | Wholesale & retail | 2025 |
| Broadbridge Associates Limited | Professional & scientific | 2024 |
| Broadwin Construction Ltd | Construction | 2019 |
| Brook Valley Ltd | Agriculture & fishing | 2013 |
| Brookridge Property Letting Limited | Real estate | 2013 |
| Brooks Automotive Limited | Professional & scientific | 2020 |
| Bryony's Beauty Limited | Other services | 2014 |
| BT Electrical & Lighting Limited | Construction | 2017 |
| Buildbetter Construction Ltd | Construction | 2023 |
| Built to Specification Limited | Construction | 2012 |
| Business Mindscapes Limited | Professional & scientific | 2010 |
| Butcher Marine Surveys Ltd | Professional & scientific | 2022 |
| Butlers Garden Machinery Ltd | Wholesale & retail | 2019 |