| Bowen T/As Ascalon Ltd | Construction | 2024 |
| Box Basildon Ltd | Arts & recreation | 2024 |
| Boxshift Collective Ltd | Wholesale & retail | 2026 |
| Boxxcoffee Thurrock Ltd | Hospitality | 2025 |
| BPM Trans Ltd | Transport & logistics | 2022 |
| BPS Plumbing and Heating Ltd | Construction | 2021 |
| BPS1 Properties Ltd | Real estate | 2023 |
| BR K9 Security Ltd | Administrative & support | 2025 |
| BRA Consulting Limited | Information & communication | 2021 |
| Bradleigh Industrial Limited | Manufacturing | 1997 |
| Bradma Ltd | Health & social care | 2022 |
| Bradstreet Consultancy Ltd | Professional & scientific | 2024 |
| Brafi and Co Ltd | Health & social care | 2011 |
| Branch Associates Epcs Ltd | Real estate | 2023 |
| Brand House Group Limited | Professional & scientific | 2020 |
| Branddeft Ltd | Professional & scientific | 2022 |
| Bravovita Ltd | Hospitality | 2020 |
| BRB Buy to LET Limited | Real estate | 2023 |
| Breaffy Social Media and Consulting Limited | Real estate | 2010 |
| Breathe Luxury Group Ltd | Wholesale & retail | 2019 |
| Breco Trans Ltd | Transport & logistics | 2019 |
| Breese Technologies Ltd | Administrative & support | 2016 |
| Breeze Line Ltd | Wholesale & retail | 2025 |
| Brent Way Development Limited | Real estate | 2023 |
| Brenthaul Global Logistics Limited | Transport & logistics | 2026 |
| Brentwood Bathrooms Limited | Agriculture & fishing | 2026 |
| Brexit Medicare Ltd | Health & social care | 2021 |
| Bri&Ps Care Ltd | Public administration | 2025 |
| Bricks&Beams Constructions Limited | Construction | 2026 |
| Bridge Court (Grays) RTM Company Limited | Households | 2019 |
| Bridge Freeholder Limited | Extraterritorial | 2015 |
| Bridgewave UK Limited | Hospitality | 2025 |
| Brigade Construction Ltd | Construction | 2012 |
| Bright Global Health Care Services Limited | Health & social care | 2016 |
| Bright Kids Childcare Ltd | Health & social care | 2026 |
| Bright Loop Limited | Construction | 2020 |
| Bright Objective Ltd | Transport & logistics | 2020 |
| Brightside Constructs Limited | Construction | 2025 |
| Briialiapis Limited | Other services | 2019 |
| Brikon Ltd | Construction | 2026 |
| Brilloconnetz Limited | Information & communication | 2016 |
| Brilo Trans Ltd | Transport & logistics | 2015 |
| Brinder Bhogal Limited | Health & social care | 2016 |
| Bristol Opus Leadership College Limited | Education | 2025 |
| Brit Security Limited | Administrative & support | 2021 |
| Britamin UK Limited | Manufacturing | 2026 |
| Britannia Shoes Ltd | Wholesale & retail | 2018 |
| British Nigerian Safeguarding Consortuim Ltd | Health & social care | 2019 |
| Britisqual Ltd | Education | 2024 |
| Briton Luggage Depot Ltd | Wholesale & retail | 2019 |
| Brittany Healthcare Services Ltd | Health & social care | 2025 |
| Broad and Extensive Property Ltd | Households | 2024 |
| Broad Money Payment & Digital Services Limited | Financial services | 2020 |
| Broadbents LLP | | 2012 |
| Broadlam Healthcare Services Limited | Wholesale & retail | 2018 |
| Broadway Hand Car Wash Ltd | Wholesale & retail | 2020 |
| Broadway Pizza Ltd | Hospitality | 2015 |
| Broadway Property Solutions Limited | Real estate | 2022 |
| Broken Crown Ltd | Construction | 2025 |
| Bromat Logistics Ltd | Wholesale & retail | 2019 |
| Bromley LET Limited | Real estate | 2024 |
| Brompton Sweets Limited | Wholesale & retail | 2017 |
| Brook Habitat Limited | Construction | 2020 |
| Brook Park Limited | Construction | 2020 |
| Brook Village Limited | Construction | 2020 |
| Brookes Accounting Services Limited | Professional & scientific | 2002 |
| Brookview Investments Ltd | Real estate | 2017 |
| Broottherrs Ltd | Construction | 2025 |
| Brother Projects Ltd | Construction | 2019 |
| Brotherhood Speed Ltd | Transport & logistics | 2021 |
| Brothers Haulage Ltd | Transport & logistics | 2017 |
| Brownish Ltd | Information & communication | 2020 |
| Brunswick Consultancy Limited | Information & communication | 1997 |
| Bryce Holdings Limited | Real estate | 2023 |
| BSB Developments Southern Limited | Construction | 2020 |
| BSC Consulting Ltd | Professional & scientific | 2010 |
| BSS Signs Limited | Construction | 2016 |
| BTB Consults Ltd | Professional & scientific | 2011 |
| BTD Builders Limited | Construction | 2024 |
| BTI Transport Ltd | Transport & logistics | 2025 |
| BTL Property Comms Ltd | Real estate | 2025 |
| Buan Enterprises Limited | Wholesale & retail | 2022 |
| Bubbyco Ltd | Transport & logistics | 2024 |
| Bubus Properties and Investment UK Limited | Real estate | 2020 |
| Buckley’S Transport Solutions Ltd | Transport & logistics | 2026 |
| Buckthorn Estates Ltd | Construction | 2004 |
| Buckwell Ltd | Wholesale & retail | 2025 |
| Bucur Services Ltd | Transport & logistics | 2023 |
| BUD Solutions Ltd | Construction | 2025 |
| Budacuheavyduty Limited | Wholesale & retail | 2025 |
| Bude Jazz 2012 Limited | Arts & recreation | 2012 |
| Buildico Limited | Extraterritorial | 2016 |
| Building Block Consultants Ltd | Construction | 2019 |
| Building Brilliance Ltd | Construction | 2020 |
| Building Materials Stores Ltd | Wholesale & retail | 2023 |
| Building Materials Wholesale Ltd | Wholesale & retail | 2019 |
| Buildlogicsystems Limited | Construction | 2026 |
| Buildtrack Ltd | Construction | 2018 |
| Bujay Skincare Ltd | Other services | 2024 |
| Bujo Holdings Limited | Real estate | 2026 |