| Best Ingredients Limited | Agriculture & fishing | 2025 |
| Best Movers Ltd | Transport & logistics | 2022 |
| Best Properties (MK) Limited | Real estate | 2002 |
| Best Quality Services Limited | Information & communication | 2020 |
| Best Seat in the House Limited | Construction | 2009 |
| Best Seat LLP | | 2009 |
| Best Services for YOU Limited | Real estate | 2015 |
| Bestatbargains Ltd | Wholesale & retail | 2025 |
| Bestfield Care Limited | Public administration | 2022 |
| Bestfield Education Development Limited | Health & social care | 2018 |
| Bestgateway Limited | Professional & scientific | 2012 |
| Bestlevel Consulting Limited | Professional & scientific | 2008 |
| Bestlife International Ltd | Health & social care | 2024 |
| BESTSTEAKMK1 Ltd | Hospitality | 2023 |
| Bestway Tyre Ltd | Wholesale & retail | 2022 |
| Bestwell (IT) Consulting Ltd | Information & communication | 2019 |
| BET & DON Ltd | Health & social care | 2019 |
| BET 21 Online Limited | Information & communication | 2015 |
| BET3000UK Limited | Information & communication | 2010 |
| Beta Prep Ltd | Wholesale & retail | 2023 |
| Beta Recruitment Ltd | Administrative & support | 2017 |
| Beta RHO Limited | Health & social care | 2016 |
| Beta RHO Sigma Limited | Professional & scientific | 2018 |
| Betag Solutions Limited | Wholesale & retail | 2024 |
| Beth Tweddle Gym Stars Limited | Arts & recreation | 2013 |
| Bethel Childcare CIC | Health & social care | 2023 |
| Bethel Flower Ltd | Public administration | 2024 |
| Bethel Haven Ltd | Real estate | 2025 |
| Bethesda Titi Limited | Health & social care | 2025 |
| Betta Tech Air Conditioning Ltd | Energy | 2024 |
| Betta-Tech Controls Limited | Manufacturing | 2004 |
| Better Annuity Ltd | Financial services | 2011 |
| Better Best Ltd | Health & social care | 2018 |
| Better Living Management Ltd | Households | 2020 |
| Better Retirement Limited | Financial services | 2010 |
| Better Retirement Solutions Ltd | Extraterritorial | 2011 |
| Better Roofing Ltd | Construction | 2021 |
| Better Than Natural Ltd | Other services | 2016 |
| Betterhealth Bucks C.I.C. | Health & social care | 2015 |
| Betting and Gaming Council | Other services | 2019 |
| Beulah Global Outreach Ltd | Other services | 2021 |
| Bevbev Limited | Hospitality | 2019 |
| Beverage Group Limited | Hospitality | 2006 |
| Beverley Light Limited | Real estate | 2024 |
| Bevington Developments Ltd | Real estate | 2015 |
| Bevlan Office Interiors Limited | Wholesale & retail | 1991 |
| Beware the Moon Ltd | Administrative & support | 1998 |
| Bewise Building Services Limited | Construction | 2019 |
| Bexley Accessible Transport Scheme | Health & social care | 2002 |
| Bexley Metal Recycling Limited | Water & waste | 2020 |
| Bexley Skip Hire Ltd | Water & waste | 2018 |
| Beyond a Ltd | Wholesale & retail | 2025 |
| Beyond Beats Ltd | Information & communication | 2023 |
| Beyond Entertainment Ltd | Arts & recreation | 2024 |
| Beyond Images Studio Limited | Arts & recreation | 2021 |
| Beyond Pubs & Dining Ltd | Hospitality | 2022 |
| Beyond the Click Limited | Arts & recreation | 2007 |
| Beyond the Shade Limited | Wholesale & retail | 2018 |
| Bezaleel Associates Limited | Professional & scientific | 2018 |
| Bezza Take Away Limited | Hospitality | 2025 |
| BFE Group Limited | Wholesale & retail | 2024 |
| Bforblinds Ltd | Wholesale & retail | 2024 |
| BG Counters Limited | Professional & scientific | 2010 |
| BG Eurotech Limited | Wholesale & retail | 2026 |
| BGA Properties Ltd | Real estate | 2016 |
| Bghtech Ltd | Professional & scientific | 2015 |
| BH Chelsea OPS Ltd | Hospitality | 2023 |
| BH Masonry & Building Specialists Ltd | Construction | 2022 |
| BH MK Estates Ltd | Real estate | 2024 |
| BH Pest Control Ltd | Administrative & support | 2025 |
| Bharatraj Solutions Ltd | Information & communication | 2024 |
| Bhargavi's Kitchen Limited | Hospitality | 2024 |
| Bhatti Builders Ltd | Construction | 2020 |
| BHB Corporation Ltd | Construction | 2024 |
| Bhima Foods Limited | Wholesale & retail | 2020 |
| BHL Real Estate Ltd | Real estate | 2026 |
| Bhma Limited | Wholesale & retail | 1991 |
| Bhooma Ltd | Construction | 2023 |
| Bhoomi Ltd | Real estate | 2019 |
| Bhoomika Software Ltd | Information & communication | 2024 |
| Bhumi Arts and Events Ltd | Arts & recreation | 2022 |
| Bhyman Housing Ltd | Households | 2019 |
| BI Adviser Limited | Information & communication | 2014 |
| BIA Tech Ltd | Professional & scientific | 2020 |
| Bibby Medical Limited | Professional & scientific | 2023 |
| Bibi's Food Ltd | Manufacturing | 2018 |
| Bicknell Engineering Limited | Manufacturing | 1977 |
| Bicube Limited | Information & communication | 2011 |
| Bidwall Properties Ltd | Real estate | 2023 |
| Bidwell Accountancy Limited | Professional & scientific | 2010 |
| Bidwell Group Limited | Professional & scientific | 2026 |
| Bienville Group Limited | Real estate | 2015 |
| Biexpert Private Limited | Information & communication | 2010 |
| Big a Tree Specialists 21 Ltd | Administrative & support | 2021 |
| Big Boyz Pizza Ltd | Hospitality | 2025 |
| Big Brick Ltd | Wholesale & retail | 2026 |
| Big Bully UK Limited | Agriculture & fishing | 2017 |
| Big Citizen Ltd | Real estate | 2016 |
| Big COW Sports Ltd | Arts & recreation | 2013 |
| Big Data Ltd | Information & communication | 2018 |