| BPB Investments Limited | Real estate | 2024 |
| BPC Taylor Ltd | Professional & scientific | 1928 |
| BPD Drylining Ltd | Construction | 2021 |
| BPF Paint Finishers Ltd | Construction | 2008 |
| BPI Stays Ltd | Real estate | 2026 |
| BPL Build Limited | Construction | 2015 |
| BPL Building Services Limited | Wholesale & retail | 2010 |
| BPM 18 Ltd | Construction | 2018 |
| BPM Advisory Limited | Wholesale & retail | 2019 |
| BPM Catering Services Limited | Hospitality | 2003 |
| BPM Construction MK Limited | Construction | 2019 |
| BPM Logistics Ltd | Wholesale & retail | 2023 |
| BQS Certification Limited | Extraterritorial | 2014 |
| Bqsl Limited | Administrative & support | 2020 |
| BR Pureplanti Ltd | Manufacturing | 2025 |
| BRA Oasis Limited | Wholesale & retail | 2025 |
| Braai Shack Ltd | Hospitality | 2012 |
| Brabeck Limited | Information & communication | 2010 |
| Brackenwood Conservatories Ltd | Construction | 2014 |
| Brackstone Harris Limited | Arts & recreation | 2016 |
| Brad Clothes Gold Clothes Limited | Wholesale & retail | 2026 |
| Bradbury Design Ltd | Professional & scientific | 2005 |
| Bradbury Housing Ltd | Real estate | 2021 |
| Bradbury Plumbers Ltd | Construction | 2013 |
| Bradgate Developments Limited | Construction | 2001 |
| Bradkum Limited | Health & social care | 2018 |
| Bradley & Co. (Management Consultants) Limited | | 1988 |
| Bradon Soft Fruit Farm Ltd | Agriculture & fishing | 2016 |
| Bradshaw Quoin Ltd | Real estate | 2025 |
| Bradsons Limited | Professional & scientific | 2000 |
| Bradwell & Partners Accountants LLP | | 2023 |
| Bradwell Common Community Centre Limited | Households | 1986 |
| Bradwell Local Store Ltd | Wholesale & retail | 2026 |
| Bradwell Trade Ltd | Wholesale & retail | 2022 |
| Bradwellcare Limited | Health & social care | 2023 |
| Brady Harvey Limited | Professional & scientific | 2023 |
| Brafield Stores Limited | Wholesale & retail | 2011 |
| Braim’S Transport Services Ltd | Education | 2020 |
| Brain Tumour Research | Health & social care | 2013 |
| Brain UP Franchising Limited | Education | 2016 |
| Brain UP Limited | Information & communication | 2014 |
| Brain UP Tuition Milton Keynes LP | | 2018 |
| Brainbank Energy Limited | Mining & quarrying | 2014 |
| Brainfood Consulting Ltd | Administrative & support | 2011 |
| Brambles Studios Ltd | Other services | 2017 |
| Bramel Logistics Limited | Transport & logistics | 2025 |
| Brameron Ltd | Wholesale & retail | 2022 |
| Brammo Ltd | Wholesale & retail | 2021 |
| Bramptonia Limited | Professional & scientific | 1939 |
| Bramwell-Popham Limited | Administrative & support | 2021 |
| Bran Consultancy Limited | Administrative & support | 2009 |
| Branchbot Ltd. | Information & communication | 2012 |
| Brand Boosted Ltd | Professional & scientific | 2024 |
| Brand Capital Properties Limited | Real estate | 2024 |
| Brand Emotion Ltd | Administrative & support | 1983 |
| Brand H&H Limited | Wholesale & retail | 2021 |
| Brand Mission Consultancy Ltd | Other services | 2019 |
| Brand Mission Limited | Other services | 2016 |
| Brand New Day Healthcare Ltd | Health & social care | 2023 |
| Brand Pilot Limited | Professional & scientific | 2011 |
| Brand Retail Limited | Professional & scientific | 2008 |
| Brand Retail Solutions Limited | Extraterritorial | 2005 |
| Brandbase Ltd | Professional & scientific | 2024 |
| Brandblaze Limited | Construction | 2024 |
| Brandco Holdings Limited | Wholesale & retail | 2008 |
| Brandco Management Limited | Wholesale & retail | 2002 |
| Brandco Sportswear Limited | Wholesale & retail | 2010 |
| Brandenburg IP Limited | Professional & scientific | 2021 |
| Brandforce Marketing Ltd. | Arts & recreation | 2004 |
| Brandies Ltd | Real estate | 2019 |
| Brandits Ltd | Manufacturing | 2024 |
| Brandity Limited | Information & communication | 2026 |
| Brandmykitchen Limited | Information & communication | 2025 |
| Brandon Tradeco Ltd | Hospitality | 2020 |
| Brandpath Group Limited | Administrative & support | 2014 |
| Brandpath UK Limited | Wholesale & retail | 1993 |
| Brandpulse Digital Ltd | Professional & scientific | 2026 |
| Brands Just Pret Ltd | Wholesale & retail | 2026 |
| Brandsafe Ltd | Manufacturing | 2009 |
| Brandsafe Protection Ltd | Manufacturing | 2009 |
| Brandspo Ltd | Professional & scientific | 2022 |
| Brandstore Limited | Extraterritorial | 2022 |
| Brandton Cooper Film Productions and Events Ltd | Information & communication | 2019 |
| Brandward Ltd | Wholesale & retail | 2013 |
| Branfold Property Management Limited | Households | 2026 |
| Brauer Limited | Manufacturing | 2006 |
| Braun & Co. Limited | Manufacturing | 1951 |
| Brave EGG Limited | Professional & scientific | 2017 |
| Brave Frog Ltd | Administrative & support | 2018 |
| Braverman Kitchens Limited | Wholesale & retail | 2010 |
| Bravery Studio Ltd | Other services | 2017 |
| Bravo Services Limited | Transport & logistics | 2015 |
| Braydown Properties Limited | Real estate | 2003 |
| Brazen Bazaar UK Ltd | Wholesale & retail | 2025 |
| Brazilian Beauty Center Ltd | Other services | 2026 |
| BRC Logistics Limited | Transport & logistics | 2021 |
| BRD Transport Ltd | Transport & logistics | 2022 |
| BRE Business Solutions Ltd | Information & communication | 2025 |
| Bread & Olive Ltd | Wholesale & retail | 2024 |
| Break City Entertainment Ltd | Information & communication | 2025 |