| Balsa Property Group Ltd | Construction | 2025 |
| Balthazarwp Ltd | Administrative & support | 2026 |
| Baltic Asset Group + UK LLP | | 2025 |
| Baltic Asset Group Ltd | Hospitality | 2025 |
| Baltic Farming Enterprises Limited | Agriculture & fishing | 1995 |
| Baltic Football Club Ltd | Education | 2017 |
| Baltic Store Ltd | Wholesale & retail | 2023 |
| Banan Transport Ltd | Transport & logistics | 2016 |
| Bandaar Restaurant Limited | Hospitality | 2026 |
| Bando Bulls Ltd | Agriculture & fishing | 2024 |
| Banks Electrical (Cambs) Limited | Construction | 2019 |
| Banksie Limited | Administrative & support | 2021 |
| Banprop Ltd | Real estate | 2021 |
| Bantz Limited | Health & social care | 2023 |
| BAP Medical UK Limited | Wholesale & retail | 2004 |
| Bar 2010 Limited | Professional & scientific | 2001 |
| BAR2 Contracting Limited | Administrative & support | 2024 |
| BAR2 Group Limited | Professional & scientific | 2024 |
| Barabas Properties Ltd | Hospitality | 2026 |
| Baralvi Investments Ltd | Real estate | 2022 |
| Baravykas Ltd | Construction | 2026 |
| Barb Home Limited | Wholesale & retail | 2026 |
| Barbecue Grill Limited | Hospitality | 2025 |
| Barber in Bottle Limited | Wholesale & retail | 2021 |
| Barberpod Limited | Other services | 2018 |
| Bardo (Midlands) Limited | Mining & quarrying | 1992 |
| Barefoot Life Limited | Administrative & support | 2012 |
| Barg Limited | Professional & scientific | 2004 |
| Bargains Basket Ltd | Wholesale & retail | 2026 |
| Bargainworlduk Limited | Wholesale & retail | 2012 |
| Barham Integrated Services Limited | Professional & scientific | 2026 |
| Baris 1975 Ltd | Transport & logistics | 2025 |
| Barkaitis&Co Ltd | Wholesale & retail | 2024 |
| Barkastrans Ltd | Transport & logistics | 2025 |
| Barker Hunt Home Limited | Wholesale & retail | 2025 |
| Barletta Catering UK Limited | Hospitality | 2020 |
| Barley Court Developments Ltd | Construction | 2015 |
| Barley Park Holdings Ltd | Financial services | 2009 |
| Barley Park Limited | Hospitality | 2005 |
| Barn Garden & Aquatic Centre Limited | Wholesale & retail | 2003 |
| Barnack Confectionery Limited | Wholesale & retail | 2008 |
| Barnack Estates Employee Trustees Limited | Other services | 2021 |
| Barnack Estates Holdings Limited | Financial services | 2020 |
| Barnack Estates UK Limited | Construction | 1987 |
| Barnby Road (Newark) Limited | Construction | 2023 |
| Barnes Financial Holdings Limited | Financial services | 2025 |
| Barnes Training Ltd | Health & social care | 2023 |
| Barnham Residents Company Limited | Households | 2003 |
| Barnstock Properties Limited | Real estate | 2020 |
| Barnstock Property Management Ltd | Real estate | 2005 |
| Barnwell Trailers Limited | Wholesale & retail | 2003 |
| Barnwood Developments (Lincs) Ltd | Construction | 2024 |
| Barnwood Developments Ltd | Construction | 2024 |
| Barrand Holdings Ltd | Construction | 2017 |
| Barrett Coach Tours Ltd | Administrative & support | 2020 |
| Barretts Lettings and Investments Ltd | Real estate | 2022 |
| Barrettsholdings Ltd | Hospitality | 2024 |
| Barrick Electrical Ltd | Construction | 2022 |
| Barristerwines Ltd | Wholesale & retail | 2025 |
| Barron Electrical Ltd | Construction | 2025 |
| Barrowfield Ltd | Wholesale & retail | 2023 |
| Barsby Cooked Meats Limited | Wholesale & retail | 2016 |
| Bart Tech Ventilation Ltd | Construction | 2020 |
| Bartelina Haulage Ltd | Transport & logistics | 2023 |
| Barti and Uncled Ltd | Transport & logistics | 2025 |
| Bartorama Limited | Real estate | 2022 |
| Bartq-Speed Ltd | Transport & logistics | 2026 |
| Bartzano Estates Limited | Real estate | 2019 |
| Bartzano Holdings Limited | Real estate | 2001 |
| Barwen Health Care Solutions Ltd | Wholesale & retail | 2025 |
| BAS Insights Ltd | Information & communication | 2023 |
| Base Contractors UK Limited | Construction | 2009 |
| Baselcox Limited | Professional & scientific | 2021 |
| Bash Cars Ltd | Wholesale & retail | 2024 |
| Basham & Sons Ltd | Wholesale & retail | 2026 |
| Bashi Enterprise Ltd | Wholesale & retail | 2026 |
| Bashir Property Ltd | Real estate | 2025 |
| Basicsofa Ltd | Professional & scientific | 2020 |
| Basildov Ltd | Professional & scientific | 2017 |
| Basis Services UK. Ltd | Extraterritorial | 2013 |
| Basis UK Limited | Professional & scientific | 2004 |
| Bask Studio Ltd | Wholesale & retail | 2026 |
| Basons & Co Ltd | Wholesale & retail | 2022 |
| Bass Group Limited | Financial services | 2020 |
| Bass Group Property Investments Limited | Real estate | 2017 |
| Bassie Boutique Ltd | Health & social care | 2025 |
| Batchelor Holdings Ltd | Financial services | 2025 |
| Bath Property Maintenance Ltd | Construction | 2022 |
| Batrans Ltd | Transport & logistics | 2014 |
| Battery City Limited | Professional & scientific | 2006 |
| Bauer Consumer Media Limited | Professional & scientific | 1974 |
| Bauer Corporate Services UK LP | | 2008 |
| Bauer Digital Radio Limited | Information & communication | 1985 |
| Bauer Global Services Limited | Administrative & support | 2023 |
| Bauer Group Secretariat Limited | Information & communication | 1968 |
| Bauer Media Audio Limited | Professional & scientific | 2019 |
| Bauer Radio Limited | Professional & scientific | 1978 |
| Baumann's Plans Ltd | Real estate | 2023 |
| Baumer HHS Limited | Manufacturing | 1997 |
| Baxter and King Building Limited | Construction | 2014 |