| Barnyard Property Lettings Limited | Real estate | 2026 |
| Barnyard Property Ltd | Construction | 2020 |
| Baron TA Consultancy Limited | Information & communication | 2020 |
| Baronarques Limited | Construction | 2023 |
| Barrass Software Ltd | Information & communication | 2026 |
| Barrett Waspe Developments Ltd | Real estate | 2022 |
| Barrier Point Communications Limited | Information & communication | 2011 |
| Barrier Services Limited | Financial services | 2024 |
| Barrows Repair Services (BRS) Ltd | Wholesale & retail | 2022 |
| Barry Whelan T Shop Limited | Wholesale & retail | 2026 |
| Barry Whelan Tech Services Ltd | Wholesale & retail | 2025 |
| Barss Services Ltd | Construction | 2025 |
| Barstech IT Solutions Ltd. | Information & communication | 2019 |
| Bartley Balmoral Ltd | Hospitality | 2018 |
| Bartley Cars Limited | Hospitality | 2023 |
| Bartley Services Ltd | Other services | 2022 |
| Barton Construction Services Ltd | Construction | 2025 |
| Barton Place Holdings Ltd | Professional & scientific | 2009 |
| Barton Place Limited | Health & social care | 2002 |
| Barwaaqo MK Ltd | Wholesale & retail | 2019 |
| Based Audio Ltd | Information & communication | 2025 |
| Basf Coatings UK Limited | Wholesale & retail | 2023 |
| Bashfod International Limited | Health & social care | 2018 |
| Bashia AG Limited | Professional & scientific | 2025 |
| Basic Plumbing & Electrical Supply Ltd | Wholesale & retail | 2022 |
| Basiliah Property Holdings Ltd | Real estate | 2025 |
| Bask Limited | Construction | 2017 |
| Basra IT Limited | Education | 2012 |
| Bass & West Holdings Ltd | Financial services | 2021 |
| Bastian Lloyd Morris LLP | | 2007 |
| Bastic Ltd | Wholesale & retail | 2023 |
| Bastinra Ltd | Wholesale & retail | 2016 |
| Bastinra Ventures Ltd | Financial services | 2025 |
| Bastion Digital Consulting Ltd | Professional & scientific | 2019 |
| Bastionchoice Limited | | 1977 |
| BAT Aviation Ltd | Manufacturing | 2016 |
| Batavi Volantes Ltd | Financial services | 2025 |
| Bateman Plumbing and Heating Ltd | Construction | 2023 |
| Batesi -Bagonenge Attorneys Ltd | Professional & scientific | 2019 |
| Batford Mill Investments Limited | Administrative & support | 1971 |
| Bath Doctor Limited | Administrative & support | 2017 |
| Bathworks Limited | Wholesale & retail | 2003 |
| Batmus Ltd | Health & social care | 2016 |
| Battenfeld Gloucester Europe Limited | Manufacturing | 1968 |
| Battenfeld UK (Holdings) Limited | Professional & scientific | 1985 |
| Battlefield Journey Limited | Administrative & support | 2005 |
| Baukultur Limited | Wholesale & retail | 2021 |
| Bavisahi Solutions Limited | Information & communication | 2015 |
| Bawm Arts and Culture CIC | Education | 2024 |
| BAX Best Limited | Information & communication | 2020 |
| Baxter & Adams Brickwork Contractors Limited | Construction | 2017 |
| Baxter Financial Limited | Financial services | 2018 |
| Bayantech Limited | Information & communication | 2025 |
| Bayleaf Management LLP | | 2014 |
| Baynes & Associates Ltd | Information & communication | 2011 |
| Bays Court Residents (Edgware) Limited | Households | 1974 |
| Baytul ILM Milton Keynes Limited | Education | 2009 |
| Baytul ILM Secondary School | Education | 2021 |
| Bayview Care Ltd | Health & social care | 2021 |
| Baywa R.E. Operation Services Limited | Manufacturing | 2014 |
| Baywatch Properties Limited | Real estate | 2001 |
| BB Truck & Van Sales Limited | Wholesale & retail | 2021 |
| BBB Holdings Ltd | Professional & scientific | 2016 |
| BBD Foods Ltd | Hospitality | 2020 |
| Bbfa Hubs (Trading) Ltd | Arts & recreation | 2025 |
| Bbfs Investments Ltd | Real estate | 2024 |
| Bbmo Holdings Limited | Financial services | 2023 |
| BBO82 Logistic Ltd | Transport & logistics | 2017 |
| Bbrc Properties Ltd | Construction | 2022 |
| Bbss Construction Limited | Construction | 2024 |
| BC Building and Renovations Ltd | Construction | 2020 |
| BC Investek Ltd | Real estate | 2026 |
| BC Professional Services Limited | Professional & scientific | 2018 |
| BCA Marketing Limited | Professional & scientific | 2008 |
| Bcass Limited | Administrative & support | 2018 |
| BCB Consulting Solutions Ltd | Administrative & support | 2020 |
| BCB Crafts Ltd | Arts & recreation | 2026 |
| Bcbcommunications Limited | Information & communication | 2020 |
| BCG Building Services Ltd | Construction | 2018 |
| BCK Consultants Ltd | Information & communication | 2020 |
| BCS Cargo Services Limited | Transport & logistics | 2016 |
| BCS Credit Ltd | Wholesale & retail | 2018 |
| BCS Global Ltd | Professional & scientific | 2020 |
| BCW 23 Limited | Administrative & support | 2018 |
| BD Restaurants Ltd | Hospitality | 2021 |
| BDA16 Services Ltd | Other services | 2019 |
| Bdass Group Ltd | Financial services | 2019 |
| Bdellion Cloud Services Limited | Information & communication | 2021 |
| Bdellion Properties Limited | Real estate | 2022 |
| BDM Business Solutions Limited | Professional & scientific | 2004 |
| BDM Rush Ltd | Transport & logistics | 2025 |
| BDM Technology Limited | Information & communication | 2013 |
| BDS Audio Visual Limited | Manufacturing | 2013 |
| BDU Group Ltd | Arts & recreation | 2026 |
| BE a Pineapple Limited | Professional & scientific | 2016 |
| BE Blessed 7 Limited | Arts & recreation | 2012 |
| BE Bold Clothing Ltd | Wholesale & retail | 2023 |
| BE Bold LC Ltd | Information & communication | 2020 |
| BE Conscious Consulting Ltd | Health & social care | 2024 |
| BE Looney Events Ltd | Hospitality | 2026 |