| ASK Wellness Ltd | Professional & scientific | 2025 |
| Aslan 1965 Limited | Arts & recreation | 2023 |
| ASM Management Services Ltd | Professional & scientific | 2026 |
| ASM Retailers (UK) Ltd | Wholesale & retail | 2020 |
| Asmith Properties Ltd | Real estate | 2022 |
| ASP Property Maintenance Limited | Administrative & support | 2018 |
| Aspect Construction & Carpentry Ltd | Construction | 2018 |
| Aspect Fire & Security Limited | Public administration | 2012 |
| Aspects Glazing Limited | Construction | 2015 |
| Aspects Plumbing & Property Services Limited | Construction | 2023 |
| Aspen Commercial Finance Ltd | Financial services | 2022 |
| Aspen Park Residents Association Limited | Households | 2001 |
| Aspen Party Wall Surveyors Ltd | Construction | 2019 |
| Aspen Rose Accountancy Ltd | Professional & scientific | 2020 |
| Aspenridge Limited | Professional & scientific | 2022 |
| Aspira Natura Ltd | Wholesale & retail | 2024 |
| Aspirare Consulting & Sports Solutions Limited | Professional & scientific | 2025 |
| Aspire Impact Ltd | Professional & scientific | 2026 |
| Aspirina Limited | Transport & logistics | 2025 |
| Aspley Group Holdings Limited | Financial services | 2022 |
| Aspley Group LLP | | 2022 |
| Aspworks Limited | Information & communication | 2024 |
| Assetmix Limited | Professional & scientific | 2015 |
| Assim Dermatology Ltd | Health & social care | 2021 |
| Assistify Ltd | Administrative & support | 2024 |
| Association of Construction Trainers CIC | Education | 2023 |
| Association of Singer Car Owners | Extraterritorial | 2018 |
| Assured Building and Property Maintenance Limited | Construction | 2014 |
| Assured Medical Recruitment Limited | Health & social care | 2012 |
| Assurevia Ltd | Professional & scientific | 2025 |
| Assuritech Ltd | Wholesale & retail | 2025 |
| Asteelflash (Bedford) Limited | Manufacturing | 1987 |
| Aster Consultants Limited | Professional & scientific | 2016 |
| Asti Limited | Transport & logistics | 2018 |
| Aston Bentley Ltd | Real estate | 2022 |
| Aston Charles Estate Agents Limited | Real estate | 2014 |
| Aston Corporate Limited | Professional & scientific | 2020 |
| Aston Recruitment & Training Limited | Education | 2004 |
| Aston Windows (Bedford) Ltd | Construction | 2008 |
| Astral Placemaking Group Limited | Administrative & support | 2024 |
| Astral Software Limited | Real estate | 2008 |
| Astrimar Ltd | Professional & scientific | 2009 |
| Astwood Autos Ltd | Wholesale & retail | 2020 |
| Astwood Coachworks Ltd | Wholesale & retail | 2025 |
| Astwood Consult Limited | Administrative & support | 2024 |
| Astwood Consultants Limited | Professional & scientific | 2022 |
| Astwood Skin Clinic Ltd | Other services | 2023 |
| AT Nails Spa Ltd | Other services | 2022 |
| AT Your Side Care Ltd | Health & social care | 2023 |
| Atabey Catering Ltd | Hospitality | 2023 |
| ATC Globalwide Limited | Transport & logistics | 2023 |
| Atcha Studio Ltd | Arts & recreation | 2018 |
| Atelier Arco Xiii Ltd | Other services | 2026 |
| Ateyie Ltd | Health & social care | 2026 |
| Athena Building Solutions Ltd | Construction | 2022 |
| Athena Children's Services Limited | Health & social care | 2017 |
| Athena Family Services Limited | Health & social care | 2020 |
| Athena Housing and Support Limited | Health & social care | 2012 |
| Athena Painting Contractors Ltd | Construction | 2018 |
| Athene Noctua Property Specialist Hub Ltd | Professional & scientific | 2018 |
| Athlytix IP Ltd | Information & communication | 2026 |
| Athreya Consulting Services Ltd | Information & communication | 2022 |
| Atina Films Ltd | Extraterritorial | 2012 |
| ATK - Architecture & Management Ltd. | Professional & scientific | 2011 |
| Atko Holdings Limited | Financial services | 2026 |
| Atko Investments Ltd | Financial services | 2026 |
| Atko Management Services Ltd | Professional & scientific | 2025 |
| ATL Building Ltd | Administrative & support | 2013 |
| Atlanta Packaging Company Limited | Wholesale & retail | 2005 |
| Atlantic Civils Ltd | Construction | 2025 |
| Atlantis Capital Ltd | Real estate | 2023 |
| Atlas Climate Technology Ltd | Construction | 2022 |
| Atlas Environmental Limited | Water & waste | 2009 |
| Atlas Skip & Grab Hire Ltd | Water & waste | 2013 |
| ATO Consulting Solutions Ltd | Transport & logistics | 2025 |
| Atos Windows & Doors Ltd | Construction | 2013 |
| Atoz Cardiac Care Ltd | Health & social care | 2025 |
| ATP Building and Maintenance Ltd | Construction | 2021 |
| ATR Housing Ltd | Real estate | 2019 |
| Atreus Associates Limited | Professional & scientific | 2020 |
| Atreya Healthcare Limited | Health & social care | 2026 |
| ATT Building Services Ltd | Construction | 2019 |
| ATT Developments Ltd | Construction | 1998 |
| Attack Pest Control Limited | Administrative & support | 2005 |
| Attention to Detailing Ltd | Wholesale & retail | 2023 |
| Attraction Pro Ltd | Professional & scientific | 2020 |
| Atunko Ltd | Professional & scientific | 2024 |
| AU Squared Ltd | Administrative & support | 2026 |
| AU2 Ltd | Professional & scientific | 2026 |
| Auberge Limited | Hospitality | 2020 |
| Auction Room Limited | Hospitality | 2012 |
| Audio Installation Services Limited | Construction | 2008 |
| Audioprint Ltd | Manufacturing | 1985 |
| Audioprint Management Limited | Extraterritorial | 2009 |
| Audit Guard AI Group Ltd | Administrative & support | 2025 |
| Augustines Flats (Bedford) Limited | Households | 1987 |
| Augusttg Ltd | Transport & logistics | 2024 |
| Aunelle (UK) Ltd | Education | 2015 |
| Aura & Lincoln Group Limited | Real estate | 2026 |
| Aura Maintenance Ltd | Construction | 2026 |