| Barrett ATS Limited | Professional & scientific | 2002 |
| Barretto Housing Limited | Real estate | 2025 |
| Barricane Apartments Ltd | Real estate | 2008 |
| Barron Heating Limited | Construction | 2002 |
| Barrowby Gate Development Ltd | Construction | 2022 |
| Barry (Muckenaugh) Limited | Extraterritorial | 2007 |
| Barton Investment Group Ltd | Real estate | 2021 |
| Barwick Law Ltd | Professional & scientific | 2021 |
| BAS13 Limited | Real estate | 2025 |
| Bascs Limited | Wholesale & retail | 2009 |
| Basecare Line Ltd | Health & social care | 2019 |
| Basement Creative Limited | Professional & scientific | 2009 |
| Baseri Ltd | Wholesale & retail | 2018 |
| Basingstoke Bison Hockey Ltd | Arts & recreation | 2025 |
| Basket Barn Ltd | Manufacturing | 2021 |
| Bassadone Automotive (Italy) Limited | Wholesale & retail | 2015 |
| Basset Spice Ltd | Hospitality | 2025 |
| Bassett Auto Bodies Ltd. | Wholesale & retail | 2018 |
| Bassett Bar & Catering Limited | Hospitality | 2003 |
| Bassett Cleansing Environmental Ltd | Administrative & support | 2022 |
| Bassett Electronic Systems Limited | Manufacturing | 1986 |
| Bassett Holdings Limited | Administrative & support | 2004 |
| Bassett Rivers Holdings Limited | Information & communication | 2018 |
| Bassett Turf Supplies Ltd | Administrative & support | 2019 |
| Bassett Wood Co. Limited(The) | Extraterritorial | 1976 |
| Bassline Consulting UK Ltd | Professional & scientific | 2026 |
| Bata 1 Motors Limited | Wholesale & retail | 2024 |
| Bate & Sons Construction Ltd | Construction | 2024 |
| Bate Construction Ltd | Construction | 2018 |
| Bates Coffee to Go Ltd | Hospitality | 2022 |
| Bath & Swindon Leaflet Distribution Ltd | Professional & scientific | 2024 |
| Bath and Power Carpentry Limited | Construction | 2003 |
| Bath Rental Properties Ltd | Real estate | 2024 |
| Bath Road (Swindon) Management Limited | Households | 2017 |
| Bathroom Mobility Solutions Ltd | Construction | 2025 |
| Bathroom Team Ltd | Construction | 2019 |
| Bathwood Properties Ltd | Real estate | 2021 |
| Bathzaar Limited | Wholesale & retail | 2019 |
| Batista Revival Ltd | Administrative & support | 2024 |
| Baton Handyman Limited | Construction | 2014 |
| Bayfield Close Management Company Limited | Real estate | 2020 |
| Baztec Limited | Information & communication | 2017 |
| BB Bomjan Ltd | Real estate | 2025 |
| BB Building Group Ltd | Construction | 2026 |
| BB LEO Ltd | Information & communication | 2020 |
| BB Management Services Limited | Real estate | 2022 |
| BB Supplements Ltd | Arts & recreation | 2026 |
| BB Training Solutions Limited | Education | 2019 |
| BB2000 Stocktaking Limited | Administrative & support | 2006 |
| Bbai Group Holding Ltd | Financial services | 2024 |
| BBS Healthcare Ltd | Health & social care | 2020 |
| BBS IT Associates Limited | Information & communication | 2008 |
| BBW Solutions Ltd | Wholesale & retail | 2025 |
| Bbwd Ltd | Real estate | 2021 |
| BC Card Trading Ltd | Wholesale & retail | 2025 |
| BC Ciobanu Ltd | Transport & logistics | 2018 |
| BC Mist Ltd | Construction | 2026 |
| BC PCB Designs Limited | Professional & scientific | 2012 |
| BCS Learning & Development Limited | Information & communication | 1971 |
| BD Swindon Ltd | Construction | 2019 |
| BDI Facilities Limited | Professional & scientific | 2022 |
| Bdjr Ltd | Transport & logistics | 2019 |
| BDN Capital Partners Ltd | Real estate | 2025 |
| BDN Grounds Ltd | Administrative & support | 2024 |
| BE Active 121 Ltd | Arts & recreation | 2018 |
| BE Awesome Limited | Wholesale & retail | 2025 |
| BE More Effective Limited | Professional & scientific | 2005 |
| BE on Cloud 9 LLP | | 2022 |
| BE Smarter Group Ltd | Information & communication | 2016 |
| Beacon Advocacy Ltd | Education | 2025 |
| Beacon Business Park Management Company Limited | Real estate | 2009 |
| Beacon Equestrian LLP | | 2023 |
| Beacon Hues Ltd | Information & communication | 2024 |
| Beadvised Ltd | Financial services | 2017 |
| Beam Movers Ltd | Transport & logistics | 2020 |
| Bean Counters (Swindon) Ltd. | Professional & scientific | 2002 |
| Bear Joy Limited | Real estate | 2024 |
| Bearnwolf Ltd | Information & communication | 2025 |
| Bearsuwant Limited | Wholesale & retail | 2002 |
| Beast Cleaning AJV Ltd | Administrative & support | 2022 |
| Beatrice OIL Limited | Extraterritorial | 1969 |
| Beau Bronzage Ltd | Wholesale & retail | 2021 |
| Beau Property Management Limited | Households | 2020 |
| Beautia Facilities Ltd | Education | 2019 |
| Beautisou Ltd | Wholesale & retail | 2022 |
| Beauty Within Millets Ltd | Other services | 2016 |
| Beauty Within Skin and Wellness Ltd | Other services | 2026 |
| Bebe Trans Logistic Ltd | Transport & logistics | 2019 |
| Beckmann Limited | Wholesale & retail | 2024 |
| Becky Garland Photography & Videography Limited | Professional & scientific | 2023 |
| Bedlington Homes Limited | Construction | 2022 |
| Bedrock Coatings Limited | Wholesale & retail | 2023 |
| Bedwell Thermal Limited | Construction | 2010 |
| BEE Beautiful Aesthetic & Beauty Ltd | Wholesale & retail | 2019 |
| Bee's Emporium Limited | Wholesale & retail | 2014 |
| Bee's Knees Cleaning Services Ltd | Administrative & support | 2026 |
| Bee-Accountable Financial Services Limited | Professional & scientific | 2025 |
| Beece Ltd | Wholesale & retail | 2023 |
| Beech Design Limited | Manufacturing | 2011 |
| Beech Geophysics Ltd | Professional & scientific | 2018 |