| BOS HQ Ltd | Financial services | 2009 |
| Bosa Malila Ltd | Real estate | 2017 |
| Boss Brickwork Limited | Construction | 2021 |
| Boss Construction Group Ltd | Construction | 2016 |
| Boss Store Mini Market Ltd | Wholesale & retail | 2026 |
| Bossman Window Cleaning Supplies Ltd | Wholesale & retail | 2026 |
| Bossway Limited | Wholesale & retail | 2019 |
| Bostan Asset Investments Ltd | Real estate | 2026 |
| Bostan Developments Limited | Construction | 2025 |
| Bostan Properties Limited | Real estate | 2024 |
| Boston Dental HQ Limited | Health & social care | 2026 |
| Boston Grill House Ltd | Hospitality | 2023 |
| Boston Prestige Taxis Ltd | Transport & logistics | 2025 |
| Botolph Investments Ltd | Wholesale & retail | 2025 |
| Botolph Tyres and Exhausts Limited | Transport & logistics | 2010 |
| Botolph Tyres Limited | Wholesale & retail | 2009 |
| Botolph Wealth Management Limited | Financial services | 2013 |
| Botolph's Yard (Stamford) Limited | Households | 2020 |
| Bottle & Board Peterborough Ltd | Wholesale & retail | 2020 |
| Bougie Luxe Limited | Wholesale & retail | 2026 |
| Bouleau Properties Ltd | Construction | 2015 |
| Boulevard View Ltd | Real estate | 2021 |
| Boulmer Residents Company Limited | Households | 2003 |
| Boundary Lane Developments Ltd | Real estate | 2020 |
| Bourgault Tillage Tools (BTT) UK Limited | Wholesale & retail | 2021 |
| Bourne & Axam Developments Ltd | Construction | 2020 |
| Bourne 4 Heat Ltd | Construction | 2025 |
| Bourne Pizza and Kebabs Ltd | Hospitality | 2022 |
| Bournemouth Building Limited | Construction | 2014 |
| Boutique SIX Limited | Other services | 2010 |
| Boutiquette Limited | Wholesale & retail | 2025 |
| Bovi Ltd | Transport & logistics | 2024 |
| Bovington Residents Company Limited | Households | 2002 |
| BOW Windows Apartments Limited | Real estate | 2005 |
| Bowden Homes Ltd | Real estate | 2024 |
| Bowfield Capital Property Limited | Real estate | 2016 |
| Bowyer Electrical Services Ltd | Construction | 2022 |
| Box CNC Ltd | Construction | 2022 |
| Box of Hugs London Limited | Wholesale & retail | 2021 |
| Boxed Light Holdings Limited | Financial services | 2021 |
| Boxer Networks Ltd | Information & communication | 2014 |
| Boyker Food Limited | Wholesale & retail | 2019 |
| BP Argo Ltd | Agriculture & fishing | 2016 |
| BPC Air Conditioning & Refrigeration Limited | Construction | 2024 |
| BR & K Enterprises Limited | Real estate | 2019 |
| BR2017 Ltd | Professional & scientific | 2017 |
| Brace Turner Limited | Water & waste | 2002 |
| Bracken Data Ltd | Information & communication | 2026 |
| Brackenbury (IFA) Limited | Financial services | 2001 |
| Brackenbury Investments Limited | Real estate | 2020 |
| Bradfield Developments (Cambs) Ltd | Construction | 2019 |
| Bradley Holdings & Investments Ltd | Information & communication | 2018 |
| Brainants Technology Ltd | Information & communication | 2023 |
| Brainbox Data Science Ltd | Information & communication | 2018 |
| Brainwave Designs Ltd | Information & communication | 2026 |
| Brais Studio Ltd | Wholesale & retail | 2025 |
| Brake Station Ltd | Wholesale & retail | 2011 |
| Bramach Property Limited | Construction | 2007 |
| Bramble One Ltd | Financial services | 2024 |
| Brand Hospitality Ltd | Hospitality | 2026 |
| Brand Peak Limited | Professional & scientific | 2019 |
| Brand Properties Ltd | Administrative & support | 2019 |
| Branded Flooring & Interiors Ltd | Construction | 2019 |
| Brandedsauce Ltd | Manufacturing | 2019 |
| Brannigan Fisheries Ltd | Agriculture & fishing | 2023 |
| Brant Associates Limited | Professional & scientific | 1996 |
| Braoli Ltd | Information & communication | 2025 |
| Brass Light Ltd | Wholesale & retail | 2025 |
| Braun Developments Limited | Construction | 2013 |
| Bravanti Group Ltd | Information & communication | 2025 |
| Brave Construction Ltd | Construction | 2019 |
| Braventa Ltd | Wholesale & retail | 2025 |
| Bravussolutions Ltd | Information & communication | 2024 |
| Brays Roofing Services Limited | Construction | 2013 |
| Brazenose Group Ltd | Financial services | 2019 |
| BRC Haulage Limited | Transport & logistics | 2015 |
| Breakdown Heroes Ltd | Transport & logistics | 2025 |
| Breakpoint Black Limited | Professional & scientific | 2019 |
| Bred Properties Limited | Construction | 2026 |
| Bred Property Group Limited | Administrative & support | 2025 |
| Breej Ltd | Health & social care | 2024 |
| Breelancer Ltd | Wholesale & retail | 2025 |
| Breeze Software Limited | Information & communication | 2025 |
| Brenddaisy Limited | Wholesale & retail | 2017 |
| Brents Boxing Ltd | Other services | 2020 |
| Bretton Park Healthcare Ltd | Education | 2025 |
| Bretton Park Holdings Ltd | Real estate | 2025 |
| Bretway and Icon Developments Limited | Construction | 2025 |
| Bretway Designs Limited | Professional & scientific | 2014 |
| Bretway Development Ltd | Construction | 2025 |
| Bretway Healthcare Limited | Health & social care | 2024 |
| Bretway Limited | Real estate | 2014 |
| Brezzie Ice Baths Ltd | Other services | 2024 |
| Brick & Bond Properties Ltd | Real estate | 2021 |
| Brick Vintage Interiors Ltd | Wholesale & retail | 2024 |
| Bricks and Keys Ltd | Real estate | 2021 |
| Bricktech Contractors Ltd | Construction | 2024 |
| Brickydone Ltd | Construction | 2025 |
| Bricofix Limited | Wholesale & retail | 2015 |
| Bricross Limited | Information & communication | 2014 |