| ARK Home Solutions Limited | Administrative & support | 2024 |
| Arkbe Studios Ltd | Manufacturing | 2026 |
| Armed & Gorgeous Limited | Extraterritorial | 2015 |
| Arnott Property 2017 Limited | Real estate | 2017 |
| Arrange Holdings Ltd | Financial services | 2026 |
| Arrange Spaces Ltd | Manufacturing | 2019 |
| Arrefco Ltd | Financial services | 2020 |
| Art.Parties Ltd | Extraterritorial | 2025 |
| Artclaims Limited | Financial services | 2018 |
| Artisan Aromas Limited | Manufacturing | 2015 |
| Arturi Films Limited | Information & communication | 2002 |
| Arundel Mill Management Limited | Professional & scientific | 1991 |
| Arwp Ltd | Professional & scientific | 2003 |
| ASH Heath PR & Marketing Limited | Professional & scientific | 2011 |
| Ashbourne Consulting Limited | Information & communication | 1998 |
| Ashley Giles Bronze Ltd | Wholesale & retail | 2020 |
| Ashp Covers Ltd | Manufacturing | 2025 |
| Ashridge Surveyors Ltd | Professional & scientific | 2015 |
| Ashwell Building Contractors Limited | Construction | 2002 |
| Asiapac Consultants (UK) Ltd | Extraterritorial | 2011 |
| ASK MRS S Ltd | Administrative & support | 2020 |
| Aspen Lake (81) Limited | Extraterritorial | 2007 |
| Aspiron Services Limited | Construction | 2009 |
| Assisted Startups Ltd | Professional & scientific | 2020 |
| Assorted Studio Ltd | Professional & scientific | 2021 |
| AST Pubs Limited | Hospitality | 2025 |
| Aston Down Grace Network CIC | Professional & scientific | 2024 |
| Aston Down Storage Ltd | Real estate | 2021 |
| Aston Europe Ltd | Information & communication | 2024 |
| Astrop Mews Limited | Real estate | 2006 |
| Astute Business Services Limited | Administrative & support | 2012 |
| AT Home on the Earth Limited | Professional & scientific | 2026 |
| Atelier YY Limited | Wholesale & retail | 2025 |
| Atema Ltd | Information & communication | 2017 |
| Aten Engineering Ltd | Manufacturing | 2013 |
| Athene Consulting Limited | Professional & scientific | 2020 |
| Athila Roos Ltd | Wholesale & retail | 2018 |
| Atst Property Ltd | Real estate | 2025 |
| Attacc Limited | Professional & scientific | 2018 |
| Atticus Anderson Ltd | Real estate | 2020 |
| Aurora Theatre C.I.C. | Arts & recreation | 2019 |
| Auspicious Furniture Ltd | Manufacturing | 2015 |
| Auta Group Limited | Financial services | 2018 |
| Auto-Samurai Ltd | Professional & scientific | 2010 |
| Autonumis UK Limited | Manufacturing | 2025 |
| Autoset (Production) Limited | Manufacturing | 1998 |
| Autotrack (Birmingham) Limited | Extraterritorial | 2004 |
| Auxato Limited | Administrative & support | 2015 |
| Avalis Limited | Professional & scientific | 2020 |
| Avis Electrical Ltd | Construction | 2020 |
| AVN Intelligence Ltd | Professional & scientific | 2020 |
| Avoca Planning Landscape and Development Limited | Professional & scientific | 2011 |
| Avocet Industrial Estates LLP | | 2001 |
| Avue Roofing & Joinery Ltd | Construction | 2025 |
| Aylmer Creative Group Ltd | Arts & recreation | 2023 |
| Azimuth Productions Ltd | Arts & recreation | 2020 |
| B & B Innovations Limited | Manufacturing | 2001 |
| B S Green Energy Limited | Administrative & support | 2014 |
| B&D Cotswolds Holdings Ltd | Real estate | 2024 |
| B. Prothero and Co Blacksmiths Ltd | Manufacturing | 2021 |
| B. Sindle & Sons Limited | Wholesale & retail | 2007 |
| B3R Property Ltd | Real estate | 2019 |
| Babelfish Media Limited | Manufacturing | 2025 |
| Badger Gym Consultants Ltd | Professional & scientific | 2024 |
| Badmoods Ltd | Information & communication | 2014 |
| Bailey Tempest Limited | Manufacturing | 2008 |
| Baker Hudson (Health) Ltd | Financial services | 2015 |
| Bali Funding Limited Partnership | | 2007 |
| Baliyo Ltd | Information & communication | 2022 |
| Ballinger Farms Ltd | Agriculture & fishing | 2020 |
| Ballymena Wind Park Limited | Energy | 2008 |
| Baloofah Limited | Manufacturing | 2021 |
| Balti Nailsworth Ltd | Hospitality | 2018 |
| Bambers Wind Park Limited | Energy | 1999 |
| Bancroft-Livingston Bathrooms Ltd | Construction | 2019 |
| Banyan Design Limited | Professional & scientific | 2015 |
| Baobab Projects Limited | Construction | 2004 |
| Bar Box Limited | Health & social care | 2018 |
| Barbar Nursery Ltd | Health & social care | 2010 |
| Barber Streisand Limited | Wholesale & retail | 2015 |
| Barbican Estates Limited | Real estate | 2013 |
| Barnard Builders Ltd | Extraterritorial | 2008 |
| Barnes Real Estate Limited | Real estate | 2026 |
| Barns Close Field Limited | Agriculture & fishing | 2014 |
| Barr Morris Law Ltd | Administrative & support | 2019 |
| Barrell Associates Ltd | Other services | 2018 |
| Barton END Stables Ltd | Arts & recreation | 2023 |
| Bashon Barber Ltd | Other services | 2026 |
| Basik Instincts Ltd | Wholesale & retail | 2021 |
| Bath Road Car Sales Ltd | Wholesale & retail | 2024 |
| Bathurst Limited | Wholesale & retail | 2003 |
| Bay Horse View Management Ltd | Households | 2021 |
| Baytree Square Management Limited | Households | 2025 |
| Bcdr Solutions Limited | Information & communication | 2016 |
| BCH Trading UN Limited | Wholesale & retail | 2025 |
| BCS Home Services Ltd | Construction | 2012 |
| BDP Imports Holdings Ltd | Wholesale & retail | 2018 |
| BDP Imports Limited | Wholesale & retail | 2000 |
| Beacon Strategic Land Ltd | Professional & scientific | 2025 |
| Bear Hobbies UN Limited | Wholesale & retail | 2019 |