| AI Teck Designs Limited | Information & communication | 2003 |
| Aimron CSE Ltd | Professional & scientific | 2025 |
| Aimy Beauty Ltd | Other services | 2023 |
| Air Bike Forks Limited | Manufacturing | 2020 |
| Air Control Services Limited | Construction | 2021 |
| Airborne Robotics Limited | Professional & scientific | 2017 |
| Aircraft Fuelling Supplies Limited | Wholesale & retail | 2005 |
| Airluxe Air Conditioning Ltd | Construction | 2026 |
| Airr Holdings Ltd | Real estate | 2016 |
| Aisha Fatima Ltd | Information & communication | 2017 |
| Aisr Certification Services Ltd | Wholesale & retail | 2025 |
| Aitronyx Ltd | Information & communication | 2026 |
| AJ Cars Services Limited | Transport & logistics | 2024 |
| AJ Gyms Ltd | Arts & recreation | 2025 |
| AJB Contractors Ltd | Construction | 2025 |
| AJC Auto Co Ltd | Wholesale & retail | 2025 |
| AJC Consultancy Services Ltd | Information & communication | 2010 |
| Ajiom Limited | Financial services | 2024 |
| AJP GAS and Heating Services Ltd | Construction | 2020 |
| AJP Operations Ltd | Information & communication | 2023 |
| Ajparker HR Consulting Ltd | Professional & scientific | 2026 |
| Ajsd Limited | Information & communication | 2008 |
| Ajvb Mends Property Limited | Real estate | 2024 |
| AK Vocal Training Ltd | Arts & recreation | 2020 |
| AKK Bookkeeping Limited | Professional & scientific | 2021 |
| Aknow Ltd | Information & communication | 2016 |
| AL Mehdi Medical Ltd | Health & social care | 2025 |
| Al's Composites Ltd | Manufacturing | 2024 |
| Aladdin Avan Ltd | Extraterritorial | 2019 |
| Alamso Ltd | Administrative & support | 2022 |
| Alan 2 Build Limited | Construction | 2022 |
| Albert Lauri Ltd | Professional & scientific | 2025 |
| Alchemy Bar and Lounge Ltd | Hospitality | 2023 |
| Alchemy Organic Salons Ltd | Other services | 2019 |
| Alchemy Organics Limited | Professional & scientific | 2024 |
| Alcian Blue Limited | Health & social care | 2023 |
| Aldergrove Manor Ltd | Health & social care | 2014 |
| Aldershot Ductwork Services Limited | Wholesale & retail | 1983 |
| Aldina Energy Mastery Ltd | Information & communication | 2024 |
| ALE Canine Solutions Limited | Other services | 2020 |
| Alecasflo Ltd | Hospitality | 2025 |
| Alesk.U Limited | Health & social care | 2024 |
| Alexa Elena Ltd | Other services | 2026 |
| Alexamazing Ltd | Wholesale & retail | 2025 |
| Alexandra House (Southampton) Limited | Construction | 2014 |
| Alexandre Ltd | Construction | 2022 |
| ALF 333 Ltd | Information & communication | 2024 |
| ALH Investments Ltd | Financial services | 2025 |
| Alice Brownfield Renovations Limited | Construction | 2015 |
| Alisim Transport Ltd | Transport & logistics | 2020 |
| Alistair JH Crump Ltd | Professional & scientific | 2021 |
| Alive With Ideas Limited | Professional & scientific | 2009 |
| ALL 4 Seasons Catering Limited | Hospitality | 2021 |
| ALL Aspects Letting Services Limited | Real estate | 2007 |
| ALL Aspects Tree and Garden Limited | Agriculture & fishing | 2010 |
| ALL Development Matters Ltd | Construction | 2014 |
| ALL Graphics IT Limited | Information & communication | 2002 |
| ALL Phase Fitness Ltd | Arts & recreation | 2024 |
| ALL Power and Lighting Electrical Ltd | Construction | 2009 |
| ALL Support Service Ltd | Administrative & support | 2019 |
| ALL the L'S Limited | Professional & scientific | 2014 |
| ALL Virtues Construction Ltd | Construction | 2018 |
| ALL Virtues Life Ltd | Wholesale & retail | 2019 |
| Allabush Controls Ltd | Professional & scientific | 2011 |
| Allegro's Homes and Hospice Ltd | Health & social care | 2022 |
| Allgates Automation Systems Limited | Construction | 2012 |
| Alll Financial Services Limited | Financial services | 2017 |
| Allner (UK) Ltd. | Wholesale & retail | 2006 |
| Allstar Cars Basingstoke Ltd | Transport & logistics | 2024 |
| Alma Studio of Excellence Limited | Professional & scientific | 2015 |
| Almora Tech Limited | Information & communication | 2021 |
| Alpacaru Limited | Wholesale & retail | 2026 |
| Alpha Archery Ltd | Wholesale & retail | 2025 |
| Alpha Bridge International Ltd | Information & communication | 2024 |
| Alpha Services & Supply Chain Limited | Other services | 2008 |
| Alphados Group Limited | Information & communication | 2020 |
| Alphascreen Systems Limited | Information & communication | 1997 |
| Alpma GB Limited | Wholesale & retail | 1981 |
| Alron Electrical Services Limited | Manufacturing | 2009 |
| Alron Project Ltd | Transport & logistics | 2016 |
| Alsopp Properties Ltd | Real estate | 2026 |
| Altar of Incense Ltd | Manufacturing | 2025 |
| Altaventura Investments Ltd | Real estate | 2018 |
| Alternative Dispute Resolution Limited | Administrative & support | 1991 |
| Altin Makas Basingstoke Ltd | Other services | 2024 |
| Altongate Limited | Information & communication | 1980 |
| Alvie Health Limited | Professional & scientific | 2017 |
| Alworth Construction Ltd | Construction | 2022 |
| ALY Pragnell Ltd. | Professional & scientific | 2014 |
| AM Froud Ltd | Construction | 2018 |
| AM Medics Limited | Professional & scientific | 2019 |
| AM Tactical Ltd | Wholesale & retail | 2016 |
| AM2AK Property Holdings Limited | Real estate | 2020 |
| Amanda Aldous Fine Art Ltd | Wholesale & retail | 2018 |
| Ambassador Homes London Limited | Real estate | 2010 |
| Amber Signal Services Limited | Construction | 2018 |
| Amberleigh House Limited | Construction | 2004 |
| Amberleigh Projects Limited | Construction | 2019 |
| Amberrosecoaching Ltd | Other services | 2024 |
| Amberroseva Ltd | Administrative & support | 2024 |