| BAD Monkey Media Limited | Information & communication | 2007 |
| Badge Shares Ltd | Hospitality | 2021 |
| Badger Hill (Management Company) Limited | Households | 2016 |
| Badger Hill Training & Assessment Centre Limited | Education | 2002 |
| Badham Production Services Limited | Information & communication | 2015 |
| Badmanners Limited | Information & communication | 2014 |
| Badmus Universal Ltd | Health & social care | 2025 |
| BAE Academy Ltd | Other services | 2025 |
| Baft International Ltd | Wholesale & retail | 2018 |
| BAG Terminal Limited | Administrative & support | 2024 |
| Bahanna Limited | Real estate | 2021 |
| Bahnwood Limited | Construction | 2022 |
| Bahra Consulting Ltd | Professional & scientific | 2025 |
| Bahubali Limited | Wholesale & retail | 2024 |
| Bail Enforcement Agency Limited | Administrative & support | 2001 |
| Bailey J R Limited | Financial services | 2026 |
| Bailey's Heating Company Ltd | Construction | 2015 |
| Baillie Design Management Ltd | Professional & scientific | 2021 |
| Baines Healthcare Ltd | Health & social care | 2024 |
| Bains Waste Ltd | Water & waste | 2024 |
| Bairds Building Services Ltd | Construction | 2014 |
| Baishin Limited | Real estate | 2020 |
| Baja Consulting Limited | Information & communication | 2013 |
| Baker Bros. (Jewellers) Limited | Wholesale & retail | 1987 |
| Baker Noel Bookkeeping & Payroll Limited | Extraterritorial | 2021 |
| Baker Noel Bookkeeping Limited | Extraterritorial | 2021 |
| Baker Noel Payroll Limited | Extraterritorial | 2021 |
| Baker Street Ampthill Ltd | Hospitality | 2026 |
| Bakers Trades Limited | Wholesale & retail | 2021 |
| Bako Sanctuary C.I.C. | Education | 2025 |
| Balaji Prop Limited | Real estate | 2023 |
| Balance Renovation Ltd | Construction | 2026 |
| Balancio Ltd | Information & communication | 2026 |
| Balcerzyk Sylwester 82910 Limited | Transport & logistics | 2014 |
| Balins Ltd | Wholesale & retail | 2025 |
| Ball Ventures Limited | Real estate | 2011 |
| Ballantine Percival Ltd | Information & communication | 2017 |
| Ballards Locum Limited | Health & social care | 2011 |
| Ballpix Limited | Manufacturing | 2017 |
| Balopia Limited | Arts & recreation | 2009 |
| Baltic Beauty Therapy Ltd | Other services | 2014 |
| Bambusal Limited | Construction | 2016 |
| Bancroft Psychology Limited | Health & social care | 2023 |
| Bangher Supermarket Ltd | Wholesale & retail | 2010 |
| Bangso Entertainment Ltd | Wholesale & retail | 2019 |
| Banks Electrical Ltd | Construction | 2017 |
| Banks Lodge Property Management Limited | Households | 2009 |
| Banner Fluid Power Limited | Manufacturing | 2002 |
| Bano Healthcare Limited | Administrative & support | 2025 |
| Bansall Ltd | Professional & scientific | 2016 |
| BAO BOY Limited | Hospitality | 2020 |
| Baobean Coffee Ltd | Manufacturing | 2025 |
| Baphomet Trading Limited | Wholesale & retail | 2024 |
| Bapio Limited | Other services | 2006 |
| Bapio Training Academy Limited | Education | 2012 |
| Barakat Properties Ltd | Real estate | 2025 |
| Barbato Ltd | Professional & scientific | 2023 |
| Barbiere Casanova Ltd | Other services | 2019 |
| Barco Investments Limited | Financial services | 2013 |
| Bargain Tyres (Bedford) Limited | Wholesale & retail | 2013 |
| Bark UK Online Limited | Wholesale & retail | 2018 |
| Barkers International Communications Limited | Construction | 1964 |
| Barket International Ltd | Construction | 2020 |
| Barkz & Bubbles Limited | Other services | 2021 |
| Barley Kiln (Harrold) Limited | Real estate | 2013 |
| Barnaby Philpott Music Ltd | Arts & recreation | 2025 |
| Barnard Building and Plumbing Ltd | Construction | 2023 |
| Barnets Hair Ltd | Other services | 2025 |
| Barnets Hairco Limited | Other services | 2014 |
| Barnett Investment Properties Limited | Real estate | 2019 |
| Barnett, Lawson (Trimmings) Limited | Extraterritorial | 1988 |
| Barnweil Limited | Wholesale & retail | 2015 |
| Barrett Residential Holdings Ltd | Real estate | 2026 |
| Barretts of Aspley Limited | Manufacturing | 1991 |
| Barrick Consultancy Ltd | Professional & scientific | 2025 |
| Bart.S Fleet Solution Ltd | Wholesale & retail | 2024 |
| Bartholomew Square Consulting Limited | Professional & scientific | 2016 |
| Barton Beauty Bar Ltd | Other services | 2025 |
| Barton Construction Limited | Construction | 2003 |
| Barton Contracts Ltd | Construction | 2008 |
| Barton Dog Groomers Ltd | Agriculture & fishing | 2024 |
| Barton Holdings (2025) Ltd | Financial services | 2025 |
| Barton Valeting Ltd | Other services | 2019 |
| Bartoszputz Ltd | Transport & logistics | 2018 |
| Baruch MC Limited | Real estate | 2025 |
| BAS Auto Group Ltd | Wholesale & retail | 2016 |
| Basar Meat Limited | Wholesale & retail | 2018 |
| Base Legacy Limited | Real estate | 2025 |
| Base UFH Systems Limited | Construction | 2014 |
| Basepoint Living Ltd | Real estate | 2026 |
| Bases Lane Management Company Limited | Households | 2021 |
| Baseufh Ltd | Construction | 2009 |
| Baseware Limited | Real estate | 1996 |
| Basileia Ventures Limited | Professional & scientific | 2013 |
| Basingha Limited | Real estate | 2021 |
| Basiri Ltd | Manufacturing | 2025 |
| Bassanio Ventures Limited | Financial services | 2022 |
| Bastion Consultancy Services Ltd | Information & communication | 2023 |
| Basuta Construction Limited | Construction | 2025 |
| Bates Bros (Farms) Limited | Agriculture & fishing | 1954 |