| ATG Motors Limited | Wholesale & retail | 2024 |
| Athena Solutions Limited | Information & communication | 2000 |
| Atom Affiliates Limited | Professional & scientific | 2026 |
| Atryda Ltd | Transport & logistics | 2023 |
| ATT Lettings Ltd | Real estate | 2025 |
| Atwood Electrical Limited | Construction | 2010 |
| Audrey Jordan Interiors Limited | Professional & scientific | 2021 |
| Augere Trade Ltd | Wholesale & retail | 2020 |
| Augustines House Ltd | Information & communication | 2020 |
| Aurality Limited | Information & communication | 2015 |
| Austin Automotive Ltd | Professional & scientific | 2020 |
| Austinhawk Ltd | Real estate | 2011 |
| Authentic Hospitality Ltd | Professional & scientific | 2020 |
| Auto Carriers Ltd | Transport & logistics | 2024 |
| Automiq Limited | Information & communication | 2025 |
| Automotive Wrapping Products Ltd | Wholesale & retail | 2024 |
| Autonom Services Ltd | Information & communication | 2024 |
| Autoplate Limited | | 1979 |
| AV Content Ltd | Other services | 2018 |
| Avon Specialist Vehicles Ltd | Wholesale & retail | 2012 |
| AW Funeral Services Ltd | Other services | 2022 |
| Axis Elevators Limited | Manufacturing | 1989 |
| Axxell Limited | Information & communication | 1996 |
| Ayo.Osakuade Limited | Health & social care | 2021 |
| Ayurveda Clinic & Wellness Centre Ltd | Health & social care | 2025 |
| Ayurveda Yoga Centre Ltd | Health & social care | 2025 |
| Aziz Corporation Limited(The) | Other services | 1983 |
| Aztec Shutters Ltd | Manufacturing | 2024 |
| B P Rolls (Hull) Limited | Manufacturing | 2008 |
| B P Rolls Limited | Wholesale & retail | 1988 |
| B&A Baker Ltd | Administrative & support | 2012 |
| B&B ROM Ltd | Wholesale & retail | 2026 |
| B.D.Diplock & Sons LP | | 2011 |
| Baby Sensory Andover & Winchester Ltd | Education | 2019 |
| Baby Squids Newbury & Reading Ltd | Arts & recreation | 2023 |
| Baby Squids Salisbury Ltd | Arts & recreation | 2020 |
| Back Office Support Ltd | Administrative & support | 2025 |
| Backstage Hub Ltd | Wholesale & retail | 2026 |
| Bagklaridis Ltd | Hospitality | 2024 |
| Baguette DE Moet Ltd | Wholesale & retail | 2002 |
| Baigent's Information Security Services Ltd | Information & communication | 2011 |
| Bakish Limited | Wholesale & retail | 2023 |
| Baldrick Builds Ltd | Real estate | 2023 |
| Balloons by BEE Limited | Hospitality | 2022 |
| Bamboo Chinese Ltd | Hospitality | 2021 |
| Barbering by AVE Ltd | Other services | 2026 |
| Barberspace Rentals Ltd | Other services | 2025 |
| Barc (Itmrs) Limited | Education | 1989 |
| Barc (Thruxton) Limited | Arts & recreation | 1969 |
| Barc (Toca) Limited | Arts & recreation | 2004 |
| Barc Commercial Ltd | Arts & recreation | 2017 |
| Barison Ltd | Information & communication | 2022 |
| Barley Barn Beauty Limited | Other services | 2020 |
| Barnby Moor Crematorium Limited | Other services | 2017 |
| Barrington Martin Ltd | Agriculture & fishing | 2020 |
| Bash Ecocleaners Service Hackney London Ltd | Administrative & support | 2026 |
| Bash Ecocleaners Service Ltd | Administrative & support | 2024 |
| Basingstoke Pressure Vessels and Pipework Limited | Manufacturing | 1987 |
| Basket Case Media Limited | Financial services | 2024 |
| Batson Property Holdings Ltd | Real estate | 2026 |
| Battle - Gibbs Accountancy Services Limited | Professional & scientific | 2023 |
| Battle-Gibbs Education Services Ltd | Hospitality | 2022 |
| Battle-Gibbs Engineering Ltd | Manufacturing | 2023 |
| Batyresolution Ltd | Wholesale & retail | 2025 |
| Bay Shutters Limited | Construction | 2020 |
| Bayet Assets Limited | Real estate | 2022 |
| Bayu Steel Limited | Construction | 2025 |
| Bazari Spice Limited | Hospitality | 2023 |
| BBK Boiler Services Limited | Manufacturing | 2009 |
| BCA Energy Solutions Ltd | Wholesale & retail | 2019 |
| BD Sultan Ltd | Hospitality | 2025 |
| Bd.Controls Ltd | Professional & scientific | 2024 |
| Be-You-Tiful Beauty Salon Ltd | Other services | 2022 |
| Beacon SIX Management Company Limited | Households | 1998 |
| Bear Behind Group Ltd | Administrative & support | 2025 |
| Bear Behind Ltd | Information & communication | 2018 |
| Beata Seffron Ltd | Administrative & support | 2026 |
| Beaverland Limited | Administrative & support | 1985 |
| Beck Randall & Carpenter Limited | Professional & scientific | 1996 |
| Becoming More Limited | Professional & scientific | 2025 |
| Bedell Limited | Professional & scientific | 2026 |
| Bedo Catering Ltd | Hospitality | 2026 |
| Beertap Inns Ltd. | Hospitality | 2019 |
| BEN Miles Decorating Limited | Construction | 2015 |
| Ben's Motorcycle Clothing & Workshop Ltd | Wholesale & retail | 2023 |
| Bench International (UK) Search Limited | Administrative & support | 2003 |
| Bentley Compton Consulting Ltd | Professional & scientific | 2022 |
| Benwell Communications Limited | Information & communication | 2016 |
| Berkeley Dog Beds Limited | Wholesale & retail | 2014 |
| Berkshire Facilities Services Limited | Construction | 2016 |
| Bernadette Bendall Limited | Professional & scientific | 2025 |
| Bernard Baker Limited | Information & communication | 2002 |
| Bernon Consulting Ltd | Information & communication | 2022 |
| Berwick Down Limited | Administrative & support | 1995 |
| Beryl Properties Ltd | Real estate | 2021 |
| Beryl Solutions Ltd | Information & communication | 2013 |
| Bespoke Dental Laboratory Limited | Manufacturing | 2018 |
| Bespokeclad Ltd | Construction | 2024 |
| Bessus Limited | Professional & scientific | 2021 |
| Best YOU Consulting Ltd | Professional & scientific | 2019 |