| B.L. (British Holidays) Limited | Professional & scientific | 1964 |
| Baan Thitiya (Bishop) Ltd | Hospitality | 2005 |
| Baar Baar Hertford Ltd | Hospitality | 2022 |
| Babel School of Dance Limited | Arts & recreation | 2002 |
| BACK2SPORT Ltd | Education | 2004 |
| Backslash Limited | Information & communication | 2005 |
| Bage Design Services Limited | Professional & scientific | 1976 |
| Baho Catering Ltd | Administrative & support | 2016 |
| Bailey & Bonniface Limited | Other services | 2007 |
| Bailey Media Agency Ltd | Professional & scientific | 2023 |
| Bajos Enterprises (UK) Limited | Wholesale & retail | 1995 |
| BALA1 Limited | Real estate | 2005 |
| Balmoral Data Limited | Information & communication | 1998 |
| Baltagus Ltd | Construction | 2024 |
| Baobab IT Services Limited | Wholesale & retail | 2003 |
| Bar Cafeteria Cibo Limited | Hospitality | 2011 |
| Baram Hammond Gardens Ltd | Other services | 2003 |
| Barbara Cartland DOT COM Limited | Information & communication | 1989 |
| Barberokan Ltd | Other services | 2025 |
| Barbershop HA4 Ltd | Other services | 2019 |
| Barbershop WD19 Ltd | Other services | 2019 |
| Bardell & Byrne Limited | Wholesale & retail | 2002 |
| Barkas & Molloy Ltd | Construction | 2002 |
| Barkas Ltd | Construction | 2007 |
| Barley Meadows (Cramlington) Management Company Limited | Households | 2017 |
| Barlow & Young, Limited | Professional & scientific | 1933 |
| Barnabys Florists Limited | Administrative & support | 2003 |
| Barnes Construction Services Limited | Construction | 2007 |
| Barnes Fencing Supplies Limited | Wholesale & retail | 2005 |
| Barnet Specsavers Limited | Wholesale & retail | 1994 |
| Barnet Visionplus Limited | Wholesale & retail | 1994 |
| Barnwood Park Ltd | Real estate | 2015 |
| Barra Trader Limited | Wholesale & retail | 2026 |
| Barrs Security (Locksmiths) UK Limited | Manufacturing | 2007 |
| Basicglen Limited | Real estate | 1992 |
| Bass Tech Ltd | Information & communication | 2023 |
| Batchfields Limited | Construction | 1972 |
| Bavel Properties Ltd | Real estate | 2020 |
| Bawden & Associates Limited | Administrative & support | 1999 |
| Bay Tree Maison Limited | Real estate | 2003 |
| Bay Wholefoods Ltd | Wholesale & retail | 2020 |
| Bayhill Homes Limited | Wholesale & retail | 2007 |
| Bayly Associates Ltd | Professional & scientific | 2000 |
| Bb&D Ltd | Real estate | 2004 |
| Bb&F Investments Ltd | Real estate | 2026 |
| Bb&S Properties Ltd | Real estate | 2003 |
| BDL Engineering Limited | Real estate | 1994 |
| BDM Solutions Limited | Professional & scientific | 2004 |
| BE Electrical Wholesalers Limited | Wholesale & retail | 2003 |
| Be-Digital Media Limited | Professional & scientific | 2004 |
| Beams Limited | Other services | 1993 |
| Beaubelle Properties Ltd | Real estate | 2026 |
| Beauchamp Computer Services Limited | Administrative & support | 1984 |
| Beauford Limited | Professional & scientific | 2021 |
| Beauty by Blue Ltd | Other services | 2022 |
| Beauty Technician Ltd | Other services | 2024 |
| Beauval Interiors LLP | | 2003 |
| Beazley & Beazley Creative Ltd | Professional & scientific | 2020 |
| Beck Optronic Solutions Trustees Limited | Professional & scientific | 2024 |
| Bedford Car Park Holdings Ltd | Transport & logistics | 2025 |
| Beka Associates Limited | Manufacturing | 1984 |
| Belcor Ltd | Administrative & support | 1998 |
| Belfast Real Estate Company Limited | Construction | 2021 |
| Bell Driving School Limited | Education | 2003 |
| Bell Theatre Services Limited | Information & communication | 1987 |
| Bellister Limited | Households | 2001 |
| Belwest Limited | Information & communication | 1997 |
| Benber Limited | Extraterritorial | 1989 |
| Benchmark Flooring Services Limited | Construction | 2006 |
| Bencross Limited | Professional & scientific | 1990 |
| Bennetts Convenience Limited | Wholesale & retail | 2008 |
| Bennison Facial Aesthetics Ltd | Health & social care | 2005 |
| Bentley Construction Consultancy and Services & Co | | 2005 |
| Bentley Lettings Limited | Real estate | 2006 |
| Berkhamsted School Enterprises Limited | Education | 1986 |
| Berkhamsted Town Hall Trading Limited | Wholesale & retail | 1996 |
| Berkhamsted Vision Limited | Health & social care | 2007 |
| Berry RE Limited | Real estate | 2025 |
| Berwick Holiday Centre Limited | Hospitality | 1973 |
| Bespoke Packaging Solutions Limited | Manufacturing | 2005 |
| Bespoke Project Solutions Limited | Professional & scientific | 1998 |
| Bespoke Property Solutions UK Limited | Real estate | 2006 |
| Besscars Limited | Other services | 1957 |
| Best Friends Childcare Centre Limited | Education | 2004 |
| Best Mangal Limited | Hospitality | 2026 |
| Best Theatre Arts Limited | Professional & scientific | 1999 |
| Betanal Systems Limited | Arts & recreation | 1989 |
| Betwise Ltd | Information & communication | 2003 |
| Beyond Bookkeeping Limited | Professional & scientific | 2001 |
| Bingo Bingo Supplies Limited | Wholesale & retail | 2006 |
| Binning Project Surveying Limited | Construction | 1999 |
| Binsam Limited | Professional & scientific | 1979 |
| Birch Engineering (Cuffley) Limited | Administrative & support | 1972 |
| Birchwell Limited | Construction | 1976 |
| BIS Productions Limited | Professional & scientific | 2007 |
| Bishops Stortford Chiropractic Clinic Ltd | Health & social care | 2007 |
| Bishops Stortford Specsavers Limited | Wholesale & retail | 1995 |
| Black-Out! Worldwide Ltd. | Extraterritorial | 1995 |
| Blackfile Limited | | 1982 |
| Blackrod Properties Ltd | Real estate | 2023 |