| Base Metalwork Limited | Preston | 2008 |
| Base MIX Limited | Wembley | 2002 |
| Base Mountain Construction Ltd | Birmingham | 2026 |
| Base Performance Simulators Ltd | Banbury | 2009 |
| Base Precision Ltd | Abertillery | 2021 |
| Base Shapes Ltd | Marlborough | 2026 |
| Base Signs Ltd | Crawley | 2016 |
| Base Structures Ltd | Bridgwater | 2019 |
| Base Worx Ltd | Caerdydd | 2024 |
| BASE10 Design Limited | Chippenham | 2021 |
| Basecamp Leisure Limited | Bangor | 2024 |
| Basecampers Limited | Padstow | 2011 |
| Based Upon Ltd | London | 2005 |
| Based.Cool Limited | Haslemere | 2019 |
| Baseline Office Furniture Limited | Goole | 2016 |
| Baseline Solving Expression Limited | Dagenham | 2018 |
| Baseline Sports Club Limited | London | 2025 |
| Baseline Studio Ltd | Birmingham | 2026 |
| Basell Polyolefins UK Limited | London | 1993 |
| Basement 4 U Limited | Preston | 2020 |
| Basement Bakehouse Ltd | Gravesend | 2024 |
| Basement Beer Ltd | Bristol | 2019 |
| Basement Bond Limited | Winchester | 2025 |
| Basement Textiles Limited | Royston | 2007 |
| Basenote Solutions Ltd | Chatham | 2025 |
| Basesource Commerce Ltd | London | 2025 |
| Baseworks Auto Care Ltd | Kenilworth | 2026 |
| Basf Agricultural Specialities Limited | Stockport | 1982 |
| Basf Coatings Refinish Limited | Chatham Maritme | 1957 |
| Basf Metals Recycling Limited | Gloucestershire | 1968 |
| Basf Pharma (Callanish) Limited | Stockport | 2005 |
| Basf Public Limited Company | Stockport | 1960 |
| Basford Associates Limited | Stoke On Trent | 2005 |
| Basfords Ltd | Norwich | 2001 |
| Basfu Special Fertilizer (Germany) Co., Ltd | London | 2025 |
| Bash Dining Company Limited | Cardiff | 2023 |
| Bash Mobile Auto Touch Limited | London | 2021 |
| Bash Morgan Ltd | London | 2026 |
| Bash Stone Supplies Limited | Accrington | 2024 |
| Bash'D Limited | Musselburgh | 2017 |
| Bashed Sauces UK Ltd | Dinas Powys | 2021 |
| Bashir Joinery Limited | Southgate | 2014 |
| Bashvisuals Expressions Ltd | Gainsborough | 2025 |
| Basic Batch Cookies Ltd | Gillingham | 2026 |
| Basic Elegance London Ltd | London | 2025 |
| Basic Element Brewing Limited | Cambridge | 2026 |
| Basic Premier Limited | Leicester | 2012 |
| Basic Thinking Limited | Wigston | 1996 |
| Basically Trade Limited | Burnley | 2014 |
| Basicfare Limited | Macclesfield | 1994 |
| Basics (International Marketing) Limited | Sutton Scotney, Winchester | 1986 |
| Basics Equipment Limited | Selsey | 2006 |
| Basicx Ltd | Reading | 2023 |
| Basil & Bonnet Ltd | Birmingham | 2020 |
| Basil and Dandelion Ltd | Glasgow | 2025 |
| Basil's Bakehouse Limited | Bristol | 2023 |
| Basildon Chemical Co. Limited | Abingdon | 1971 |
| Basildon Glass Limited | Wickford | 2021 |
| Basildon Printing Company Limited | South Benfleet | 1978 |
| Basildon Wheels Limited | Basildon | 2019 |
| Basilio Blacks Ltd | Tadworth | 2021 |
| Basilisk Dynamics Limited | Taunton | 2025 |
| Basilisk Joinery Ltd | Southampton | 2019 |
| Basil’S Botanicals Limited | Gravesend | 2018 |
| Basin Design Limited | Leicester | 2024 |
| Basingstoke Appliance Service Ltd | Basingstoke | 2002 |
| Basingstoke GAS & Heating Services Ltd | Hook | 2002 |
| Basingstoke Honey Limited | Basingstoke | 2023 |
| Basingstoke Packaging Limited | Thatcham | 1979 |
| Basingstoke Precision Products Limited | London | 2003 |
| Basingstoke Pressure Vessels and Pipework Limited | Andover | 1987 |
| Basiri Ltd | Bedford | 2025 |
| Basis Lighting Limited | Poole | 1991 |
| Basit Enterprises Limited | Manchester | 2023 |
| Basit Knitwear Limited | Manchester | 2008 |
| Bask Design Limited | London | 2024 |
| Bask London Ltd | London | 2026 |
| Baskerville Reactors & Autoclaves Limited | Pudsey | 2015 |
| Basket Barn Ltd | Swindon | 2021 |
| Basketdrop Ltd. | West Malling | 2018 |
| Basm (Netherlands) Chemical Group Co., Ltd | Manchester | 2024 |
| Basok Ltd | Burnham-On-Crouch | 2025 |
| Basolite Ltd | Spennymoor | 2021 |
| Bason Bridge Brewing Company Ltd | Highbridge | 2018 |
| Basra Sign & Print Limited | Chadwell Heath | 2022 |
| Bass Electrical Limited | Lincoln | 2007 |
| Bass-O-Matic Limited | London | 2016 |
| Bassaire Cleanrooms Ltd | Rossendale | 2005 |
| Bassam Abdallah Ltd | London | 2025 |
| Bassetlaw Dental Prosthetics Limited | Worksop | 2015 |
| Bassett Electronic Systems Limited | Swindon | 1986 |
| Bassett Fork Trucks Limited | Epping | 2007 |
| Bassett Installation Services Limited | London | 2014 |
| Bassett's Stonework Ltd | Morden | 2025 |
| Bassface Distribution Ltd | Macclesfield | 2017 |
| Bassi Luigi Limited | London | 2011 |
| Bassies Kitchen Ltd | Birmingham | 2024 |
| Bassini Watches Company Limited | Harrow | 2026 |
| Bassini’S Bakeries Limited | Harrow | 2020 |
| Bassra Machine Tools Limited | Birmingham | 1997 |