| BRV Technologies Limited | Wholesale & retail | 2003 |
| Brwb Fibre Ltd | Information & communication | 2020 |
| Brxconsults Ltd | Professional & scientific | 2022 |
| Bryce Trading Ltd | Financial services | 2022 |
| Bryerley Springs Limited | Arts & recreation | 2013 |
| Bryk Properties Ltd | Real estate | 2025 |
| Brylant K9 Ltd | Administrative & support | 2019 |
| Bryson Heating Limited | Construction | 2021 |
| Bryson House Ltd | Health & social care | 2018 |
| BS Certification Centre Ltd | Professional & scientific | 2019 |
| BS Heating and Plumbing Ltd | Construction | 2022 |
| BSA Property Management Ltd | Real estate | 2022 |
| Bsac World Limited | Wholesale & retail | 2020 |
| Bsav Consulting Ltd | Professional & scientific | 2019 |
| Bsdr 19 Limited | Professional & scientific | 2011 |
| BSK Software Solutions Limited | Information & communication | 2021 |
| BSM Interior Ltd | Construction | 2020 |
| Bsnl Properties Ltd | Real estate | 2023 |
| BSP Electrics Limited | Construction | 1993 |
| Bsquared Properties Limited | Real estate | 2020 |
| BSS Healthcare Ltd | Health & social care | 2025 |
| BST Property Investment Ltd | Transport & logistics | 2021 |
| BT & Co Enterprise Ltd | Real estate | 2026 |
| BT Asset Management Ltd | Real estate | 2020 |
| BT Rentals Ltd | Administrative & support | 2025 |
| BT ROY Consulting Limited | Professional & scientific | 2023 |
| Btc.Inks Limited | Information & communication | 2025 |
| BTD Healthcare Limited | Extraterritorial | 2022 |
| Btdf Limited | Health & social care | 2017 |
| BTJ Digital Ltd | Wholesale & retail | 2024 |
| Bubb Retail Consultancy Ltd | Professional & scientific | 2014 |
| Bubble Stuff Limited | Real estate | 2015 |
| Bubble Tea Haven Ltd | Wholesale & retail | 2023 |
| Bubbles Laundromat (Media) Ltd | Administrative & support | 2013 |
| BUBBLYCREATIVE8 Ltd | Wholesale & retail | 2024 |
| Buck Management Ltd | Hospitality | 2025 |
| Buckingham Consultancy Ltd | Information & communication | 2019 |
| Buckingham Court (Newport Pagnell) Residents Association Limited | Households | 2003 |
| Buckingham Court (Poole) RTM Company Limited | Households | 2026 |
| Buckingham International Group Ltd | Manufacturing | 2018 |
| Buckingham Law Practice Limited | Administrative & support | 2006 |
| Buckingham Management Company Limited | Households | 2006 |
| Buckingham Media Ltd | Information & communication | 2024 |
| Buckingham Woodcraft Ltd | Manufacturing | 2022 |
| Buckinghamshire Argyll Acquisitions Ltd | Financial services | 2025 |
| Buckinghamshire Cheese Ltd | Manufacturing | 2024 |
| Buckinghamshire Honey Company Ltd | Agriculture & fishing | 2020 |
| Buckland Surveying and Drawing Limited | Professional & scientific | 2003 |
| Bucklands Croft Management Limited | Households | 2001 |
| Bucks and Beds Cleaning Limited | Administrative & support | 2024 |
| Bucks Asset Finance Limited | Financial services | 2007 |
| Bucks Bar Hire Ltd | Hospitality | 2024 |
| Bucks Cars Ltd | Wholesale & retail | 2014 |
| Bucks Cleaning Services Limited | Water & waste | 2007 |
| Bucks Climate & Plumbing Ltd | Construction | 2026 |
| Bucks Consultancy Ltd | Information & communication | 2014 |
| Bucks Equine Construction MK Limited | Construction | 2023 |
| Bucks Futsal Club CIC | Arts & recreation | 2025 |
| Bucks GAS & Electric Ltd | Construction | 2025 |
| Bucks General Surgery Limited | Health & social care | 2012 |
| Bucks PUB Company Limited | Hospitality | 2015 |
| Bucks Real Estates Ltd | Real estate | 2022 |
| Bucks Support Services Limited | Administrative & support | 2025 |
| Buckstechi Ltd | Other services | 2021 |
| Bucovina Catering Ltd | Hospitality | 2021 |
| Budget Booking Ltd | Hospitality | 2024 |
| Budget Parcels Limited | Wholesale & retail | 2011 |
| Budget Zone Ltd | Wholesale & retail | 2025 |
| Buena Vista Developments Limited | Construction | 2023 |
| BUI Consulting Limited | Professional & scientific | 2016 |
| Build 4 Space Properties Limited | Real estate | 2022 |
| Build Class Ltd | Construction | 2023 |
| Buildcraft Recruitment Ltd | Construction | 2024 |
| Builders of MK Ltd | Construction | 2022 |
| Building Energy Solutions (PGS) Ltd | Administrative & support | 2023 |
| Building for Humanity CIC | Construction | 2017 |
| Building Insperation for Construction and Consultancy UK Limited | Construction | 2022 |
| Building Intelligence AI Limited | Information & communication | 2026 |
| Building Traders Ltd | Construction | 2022 |
| Buildings of Remembrance International Limited | Construction | 2015 |
| Buildroute Limited | Construction | 1987 |
| Buildwell Management Ltd | Professional & scientific | 2020 |
| Built for Life Ltd | Other services | 2018 |
| Built for Life Ministries | Other services | 2011 |
| Built Still Ltd | Information & communication | 2026 |
| Bukcs Limited | Health & social care | 2016 |
| Bukhari Chambers Solicitors Ltd | Extraterritorial | 2015 |
| Bule Nile Consultancy Limited | Health & social care | 2022 |
| Bulgari 2 Limited | Extraterritorial | 2025 |
| Bulgari Hotels Limited | Extraterritorial | 2025 |
| Bulkmech Distributors Ltd | Wholesale & retail | 2025 |
| Bullchamp Ltd | Wholesale & retail | 2025 |
| Bullet Force Ltd | Wholesale & retail | 2025 |
| Bullet Proof VPN Ltd | Information & communication | 2021 |
| Bullring Tavern Ltd | Hospitality | 2026 |
| Bulwell Properties Limited | Professional & scientific | 1959 |
| Bumble Bees Limited | Other services | 1994 |
| Bumblebee & Sons Limited | Transport & logistics | 2019 |
| Bumpstart Baby Shop Ltd | Wholesale & retail | 2017 |
| Bunn Limited | Wholesale & retail | 2001 |