| Biedronka Grantham Market Ltd | Wholesale & retail | 2026 |
| Big Green Box (UK) Limited | Manufacturing | 2008 |
| Big Padre Ltd | Real estate | 2020 |
| Bill Barrell Ltd | Wholesale & retail | 1983 |
| BIN Busters Ltd | Administrative & support | 2025 |
| Binbrook Hill Farm LLP | | 2017 |
| Birch and Yarn (Gifts From Nature) Limited | Wholesale & retail | 2020 |
| Bird & Co Solicitors LLP | | 2006 |
| BKS Trading Limited | Wholesale & retail | 2025 |
| Black Dog Catering and Events Limited | Hospitality | 2014 |
| Black Hound Consulting Limited | Professional & scientific | 2015 |
| Blackpeaksolutions Ltd | Information & communication | 2025 |
| Blake Consulting Limited | Professional & scientific | 2024 |
| Blake Properties Limited | Real estate | 2018 |
| Blank Table (Cambridge) Limited | Hospitality | 2023 |
| Blank Table (Elder Gate) Limited | Hospitality | 2025 |
| Blank Table (Hall Road, Norwich) Limited | Hospitality | 2025 |
| Blank Table (Hampton) Limited | Hospitality | 2024 |
| Blank Table (Merry Hill) Limited | Hospitality | 2024 |
| Blank Table (Rushden Lakes) Limited | Hospitality | 2024 |
| Blank Table (Spalding) Limited | Hospitality | 2024 |
| Blank Table 2 Limited | Hospitality | 2024 |
| Blank Table Limited | Hospitality | 2021 |
| Blankstone Plastering Limited | Construction | 2006 |
| Blankton Enterprises Ltd | Wholesale & retail | 2021 |
| Blas-Tec Group Ltd | Construction | 2020 |
| BLH Continuity Services Limited | Professional & scientific | 2017 |
| Blingcar Ltd | Transport & logistics | 2015 |
| Bliss Services (Grantham) Limited | Administrative & support | 2025 |
| Blockstate Property Management Limited | Real estate | 1999 |
| Bloodworth Investments LLP | | 2024 |
| Bloom & Breathe Aromatherapy Ltd | Health & social care | 2025 |
| Bloomsbury Bakery Ltd. | Manufacturing | 2008 |
| Blossoming Hearts Care Agency Ltd | Health & social care | 2015 |
| Blue Bridges Solicitors Ltd | Professional & scientific | 2019 |
| Blue Castle Group Limited | Professional & scientific | 2020 |
| Blue Castle Utilities Ltd | Other services | 2022 |
| Blue Cedar Grange Management Company Limited | Administrative & support | 2014 |
| Blue Things Limited | Financial services | 2015 |
| Bluebell Cottage (2026) Ltd | Financial services | 2026 |
| Blumont Healthcare Limited | Wholesale & retail | 2010 |
| Blumont Pharma Limited | Wholesale & retail | 2005 |
| Blunt by Daniel Ltd | Other services | 2023 |
| BLY Holdings Limited | Financial services | 2020 |
| Blyth Carpentry and Joinery Ltd | Construction | 2014 |
| BM & RM Consulting Ltd | Professional & scientific | 2018 |
| Boat Share Finder Limited | Information & communication | 2014 |
| Bomer Capital Limited | Financial services | 2014 |
| Bonam Buildings Ltd | Real estate | 2024 |
| Book Handyman Ltd | Construction | 2021 |
| Book Property Limited | Real estate | 2023 |
| Boole Ltd | Information & communication | 2023 |
| Boord LLP | | 2006 |
| BOP Europe Ltd | Manufacturing | 2007 |
| Borkertas Events Ltd | Arts & recreation | 2025 |
| Borkertas Promotions Ltd | Professional & scientific | 2025 |
| Born & Raised Ltd | Hospitality | 2015 |
| Boshaduppy Ltd | Wholesale & retail | 2021 |
| Boston Sleep Company Ltd | Wholesale & retail | 2023 |
| Botanicals Limited | Wholesale & retail | 2004 |
| Bourton Estate Properties Limited | Real estate | 2014 |
| Bowser & Ward Limited | Financial services | 2023 |
| Box Movers Ltd | Transport & logistics | 2023 |
| Boyd Quality Management Limited | Administrative & support | 2014 |
| BP Property Devs Ltd | Real estate | 2022 |
| BPS Joinery and Renovations Ltd | Construction | 2021 |
| Brady Consultancy Services Ltd | Professional & scientific | 2016 |
| Bramcote Group Limited | Professional & scientific | 2024 |
| Bratka Ltd | Hospitality | 2025 |
| Bravo Valets Limited | Administrative & support | 2024 |
| Breckland Supplies Ltd | Wholesale & retail | 2015 |
| Bregc Support Services Ltd | Health & social care | 2025 |
| Breglirch Ltd | Transport & logistics | 2022 |
| Bregs Care Services (BCS) Ltd | Health & social care | 2025 |
| Bregz Healthcare Services (BHS) Ltd | Administrative & support | 2025 |
| Bremco Capital Limited | Financial services | 2011 |
| Brendan Hope Ltd | Other services | 2021 |
| Brewers Electrical Limited | Construction | 2003 |
| Brewster's Brewing Company Limited | Manufacturing | 1997 |
| Brian Barlow (Services) Limited | Construction | 2023 |
| Brian Sedgley Elvins LLP | | 2008 |
| Briar Ltd | Wholesale & retail | 2022 |
| Brighton Wireworks Limited | Construction | 2025 |
| Brilliant Young Minds (Education) Limited | Health & social care | 2019 |
| Brinvale Bird Foods Limited | Agriculture & fishing | 2012 |
| Brisk Cleaning Services Ltd | Administrative & support | 2018 |
| Brisson Close Management Limited | Households | 2009 |
| Britar Ltd | Construction | 2018 |
| Britglobal Educational Group Limited | Education | 2025 |
| British Indoor Skydiving Association Limited | Other services | 2019 |
| Brittain Property Developments Ltd | Construction | 2024 |
| Britts Hairdressers Limited | Other services | 2021 |
| Britzen Education Ltd | Education | 2026 |
| Broadeaves Limited | Real estate | 2025 |
| Brook Green Consultants Limited | Professional & scientific | 2021 |
| Brooking Underwriting Limited | Financial services | 2009 |
| Brooks and Sims Limited | Construction | 2002 |
| Brookwold Limited | Real estate | 2021 |
| Broun Lindsay LLP | | 2008 |
| BRY Ice Ltd | Administrative & support | 2024 |