| Bicycle Innovations Ltd | Manufacturing | 2024 |
| Bifol Ltd | Construction | 2018 |
| Big Lion Events Ltd | Information & communication | 2023 |
| Big Story Ltd | Professional & scientific | 2026 |
| Big SUR (119 High Street) Limited | Construction | 2023 |
| Big SUR (31 High Street Opco) Ltd | Construction | 2024 |
| Big SUR (31 High Street) Limited | Construction | 2023 |
| Big SUR (Bournemouth) Limited | Construction | 2018 |
| Big SUR (Holliday Street) Limited | Construction | 2021 |
| Big SUR (Kerrfield) Limited | Construction | 2018 |
| Big SUR (Walnut Tree) Limited | Construction | 2018 |
| Bige Fintech Limited | Information & communication | 2018 |
| Bigrobbo Limited | Information & communication | 2024 |
| Bijou Merch Limited | Wholesale & retail | 2022 |
| Bike Moto Ltd | Wholesale & retail | 2018 |
| Bill Lucas Partnership Ltd | Professional & scientific | 2010 |
| Bing Bing Foods Limited | Wholesale & retail | 2022 |
| Biopharma Overseas Limited | Professional & scientific | 2012 |
| Biopharma Process Systems Limited | Professional & scientific | 1989 |
| Biopharma Technology Limited | Professional & scientific | 1997 |
| Bioteq Limited | Health & social care | 2016 |
| Birchett House RTM Company Limited | Households | 2022 |
| Bird Brothers Enterprises Limited | Hospitality | 2017 |
| Birling Manor Limited | Real estate | 2003 |
| Bison Consultancy Services Ltd | Information & communication | 2024 |
| Bitsmart Technology Ltd | Information & communication | 2019 |
| Bizdb Limited | Information & communication | 2017 |
| Bizi Club Limited | Arts & recreation | 1999 |
| Bizmin CIC | Education | 2020 |
| BJM (Hampshire) Limited | Professional & scientific | 2021 |
| BJM Dwellings Ltd | Real estate | 2015 |
| BJT (Hampshire) Limited | Professional & scientific | 2015 |
| BJT Accountants Limited | Extraterritorial | 2016 |
| BK Foster Limited | Hospitality | 2002 |
| Bkay Plumbing & Heating Limited | Construction | 2025 |
| Black Barn Farm Limited | Agriculture & fishing | 2022 |
| Black Cat Global Limited | Information & communication | 2019 |
| Black Flag Drinks Ltd | Manufacturing | 2024 |
| Black Insomnia Ltd | Manufacturing | 2018 |
| Black Kite Limited | Professional & scientific | 2007 |
| Blackbridge Wharf Limited | Real estate | 2024 |
| Blackdown Resources (UK) Limited | Administrative & support | 2013 |
| Blackwell and Moody Limited | Manufacturing | 2002 |
| Blackwell Place Holdings Limited | Health & social care | 2025 |
| Blades Motorcycles Ltd | Extraterritorial | 2024 |
| Blanche Limited | Professional & scientific | 2005 |
| Blank Canvas Training Ltd | Professional & scientific | 2018 |
| Blee International Ltd. | Information & communication | 2016 |
| Blemish Free Ltd | Other services | 2021 |
| Blended Drinks Limited | Wholesale & retail | 2020 |
| Blissful Island Care UK Ltd | Health & social care | 2024 |
| Blnk Ltd | Wholesale & retail | 2025 |
| Blockstream Ltd | Professional & scientific | 2018 |
| Bloom and Bialystock LLP | | 2003 |
| Bloom Education LLP | | 2019 |
| Bloomer & Bloomer Hair Boutique Limited | Other services | 2014 |
| Blue Badger Holdings Ltd | Administrative & support | 2019 |
| Blue Badger Wholesale Ltd | Administrative & support | 2006 |
| Blue Ball Hill Management Company Limited | Households | 2012 |
| Blue Chimera Partnership LLP | | 2015 |
| Blue Fish Construction Ltd | Construction | 2014 |
| Blue Frog Services Limited | Construction | 2017 |
| Blue Hour Coffee Limited | Manufacturing | 2024 |
| Blue Lake Consulting Structural Engineers Ltd | Professional & scientific | 2021 |
| Blue Leaf Projects Limited | Real estate | 2016 |
| Blue Peak Consulting Group Ltd | Professional & scientific | 2022 |
| Blue Rune Limited | Extraterritorial | 2023 |
| Blue Sky Endeavour Ltd | Administrative & support | 2018 |
| Blue Sphere Films Ltd | Information & communication | 2013 |
| Blue Zebra Consultancy Limited | Wholesale & retail | 2024 |
| Bluebay Southern Limited | Construction | 2015 |
| Bluebell Rooms Limited | Real estate | 2021 |
| Bluebird Penthouse Limited | Hospitality | 2019 |
| Bluebird Shot Girls Ltd | Administrative & support | 2024 |
| Bluestone Land Profits Ltd | Real estate | 2025 |
| Bluexi Limited | Professional & scientific | 2020 |
| Blunn Architects Ltd | Professional & scientific | 2018 |
| BM Psychology Ltd | Health & social care | 2021 |
| Bmec Qualifications Limited | Education | 2014 |
| Boat Projects Ltd | Manufacturing | 2024 |
| Boating Ltd | Transport & logistics | 2022 |
| Boba Moon UK Ltd | Wholesale & retail | 2022 |
| Bobby-Dowza Ltd | Professional & scientific | 2025 |
| Bocadillo Winchester Ltd | Wholesale & retail | 2023 |
| Bockmer Farm Limited | Financial services | 2017 |
| Boka Food Limited | Hospitality | 2016 |
| Bold Creative Limited | Administrative & support | 2005 |
| Bolton Lodge Residents Company Limited | Households | 2004 |
| Bomark (U.K.) Limited | Real estate | 1985 |
| BON Supplies Ltd | Wholesale & retail | 2022 |
| Bonnita Ltd | Wholesale & retail | 2025 |
| Bonnon Properties Limited | Real estate | 2024 |
| Boogaloo Homes Limited | Real estate | 2016 |
| Born Lucky Studios Ltd | Information & communication | 2026 |
| Borough Bench Holdings Limited | Financial services | 2021 |
| Borough Bench Media Limited | Professional & scientific | 2014 |
| Boss Mode Games Limited | Information & communication | 2017 |
| Boundary Mark Ltd. | Professional & scientific | 2020 |
| Boundful Limited | Health & social care | 2022 |
| Bourne Couriers Ltd | Wholesale & retail | 2017 |