| Bosii Ltd | Wholesale & retail | 2022 |
| Boss Carpets Ltd | Wholesale & retail | 2018 |
| Bossiie Ltd | Wholesale & retail | 2022 |
| Bostan Investments Limited | Real estate | 2020 |
| Bostan Lettings Ltd | Real estate | 2018 |
| Bostan Rentals Limited | Real estate | 2020 |
| Boston Law Ltd | Professional & scientific | 2025 |
| Bosworth Ventures Ltd | Transport & logistics | 2025 |
| Botifylab Ltd | Professional & scientific | 2025 |
| Boufassa Group Ltd | Professional & scientific | 2025 |
| Bounce Lighting Limited | Professional & scientific | 2024 |
| Bounty Solutions Limited | Financial services | 2025 |
| Bourneway Invest Ltd | Professional & scientific | 2010 |
| Boutique Care Homes Limited | Extraterritorial | 2017 |
| Boutique Care Shepperton Ltd | Health & social care | 2010 |
| Boutique Holdco 1 Ltd | Financial services | 2022 |
| Boutique Holdco 2 Ltd | Financial services | 2022 |
| Boutique Holdco 3 Ltd | Financial services | 2023 |
| Boutique Propco (Broadstairs) Ltd | Construction | 2017 |
| Boutique Propco (Burgess Hill) Ltd | Construction | 2021 |
| Boutique Propco (Hythe) Ltd | Construction | 2022 |
| Boutique Propco (Newmarket) Ltd. | Construction | 2017 |
| Boutique Propco (Shepperton) Ltd | Real estate | 2020 |
| BOV Holding Ltd | Financial services | 2019 |
| Bovis & Sons Limited | Professional & scientific | 2021 |
| Bovpartners Ltd | Construction | 2017 |
| Bovproperty Ltd | Real estate | 2022 |
| Bowday Investments Ltd | Real estate | 2019 |
| Bowl and Booze Ltd | Hospitality | 2024 |
| Bowutifulears Ltd | Arts & recreation | 2023 |
| Box Financial Services Limited | Financial services | 2021 |
| Box-Y the Party Box Co Ltd | Wholesale & retail | 2020 |
| Boxedstars Limited | Manufacturing | 2025 |
| Boxwiser Limited | Wholesale & retail | 2024 |
| Boyd Taverns Limited | Hospitality | 2019 |
| BP Jointers Ltd | Construction | 2023 |
| BP Ongar Ltd | Wholesale & retail | 2020 |
| BPC Pest Control Ltd | Extraterritorial | 2016 |
| BPC Roofing Limited | Extraterritorial | 2020 |
| BPS Mids Ltd | Health & social care | 2026 |
| BR Properties Improvement and Investment Ltd | Real estate | 2024 |
| Bradford Go Ltd | Wholesale & retail | 2025 |
| Bradgate Lighting & Furnishings Limited | Wholesale & retail | 2003 |
| Bradmeg Designs Ltd | Health & social care | 2014 |
| Brailsford Global Ltd | Wholesale & retail | 2026 |
| Braimah Holdings Ltd | Financial services | 2022 |
| Braintree & Amersham Management Limited | Real estate | 2012 |
| Brajeff Developments Ltd | Real estate | 2015 |
| Brajeff Flooring Limited | Construction | 1980 |
| Brambles Close Felsted Management Limited | Households | 2023 |
| Brambles Property Group Ltd | Real estate | 2024 |
| Brampton Manor Newmarket Ltd | Health & social care | 2020 |
| Brand Affection UK Ltd | Wholesale & retail | 2019 |
| Branddy Limited | Administrative & support | 2019 |
| Branded Toiletries Ltd | Wholesale & retail | 2016 |
| Brandon Steel Holdings Limited | Real estate | 1998 |
| Brandon's Electrical Limited | Households | 2016 |
| Brands-Eu Limited | Wholesale & retail | 2016 |
| Brandslink Ltd | Wholesale & retail | 2019 |
| Brandsmits Ltd | Information & communication | 2025 |
| Branduks Ltd | Wholesale & retail | 2024 |
| Brar Property Management Limited | Real estate | 2025 |
| Brassly Limited | Wholesale & retail | 2024 |
| Brave VIC Builders Limited | Construction | 2010 |
| Bravo Pharma (UK) Ltd | Wholesale & retail | 2016 |
| Braxtons Plumbing & Heating Limited | Construction | 2026 |
| Breadcrumbs Community CIC | Professional & scientific | 2026 |
| Bredmars Ltd | Wholesale & retail | 2020 |
| Breeze Carers Ltd | Health & social care | 2023 |
| Breezeway Ltd | Real estate | 2025 |
| Breezys Ltd | Real estate | 2025 |
| Breknall & Mather Limited | Administrative & support | 2013 |
| Brenbar Building Services Limited | Extraterritorial | 2015 |
| Brenbar Electrical Services Limited | Construction | 1998 |
| Brendan Krasniqi Transport Limited | Transport & logistics | 2010 |
| Brennan & Burch Ltd | Professional & scientific | 2017 |
| Brentwood Blinds Limited | Wholesale & retail | 2015 |
| Brentwood Builders Merchants Limited | Wholesale & retail | 2022 |
| Brentwood Contractors Ltd | Construction | 2006 |
| Brentwood Glass & Glazing Ltd | Construction | 2022 |
| Brentwood Road Properties Limited | Real estate | 2001 |
| Brett Irwin Editing Limited | Information & communication | 2007 |
| Brewster One Limited | Professional & scientific | 2021 |
| Brexit Properties Ltd | Real estate | 2019 |
| Brexitransport Ltd | Transport & logistics | 2019 |
| BRH Painting & Decorating Ltd | Construction | 2015 |
| Bri's Kitchen Ltd | Wholesale & retail | 2021 |
| Brian 2 FAB Construction Ltd | Manufacturing | 2022 |
| Brian James Celine Limited | Hospitality | 2024 |
| Brian Oak Limited | Wholesale & retail | 2020 |
| Brick Box Investments Ltd | Real estate | 2021 |
| Brick Collectable Limited | Manufacturing | 2025 |
| Brick DR Stafford Ltd | Construction | 2013 |
| Brick Lane Bagel Company (Collier ROW) Limited | Hospitality | 2025 |
| Brick Lane Bagel House Limited | Wholesale & retail | 2019 |
| Brick Lane Coffee Limited | Manufacturing | 2024 |
| Brick Nest Property Ltd | Real estate | 2025 |
| Brick Slip Makers Limited | Wholesale & retail | 2023 |
| Brickbond Developments Ltd | Construction | 2022 |
| Brickhill Developers Ltd | Construction | 2023 |