| Afilia Ltd | Professional & scientific | 2012 |
| AFM Advisory Ltd | Other services | 2021 |
| African Sherpa Global Ltd | Professional & scientific | 2021 |
| AG Landscapes Hampshire Limited | Administrative & support | 2026 |
| Ageless Health Limited | Professional & scientific | 2012 |
| Agency One Ltd | Professional & scientific | 2014 |
| Agenttoolkit Ltd | Real estate | 2025 |
| Agfora Ltd | Professional & scientific | 2015 |
| Agile Global Services Limited | Information & communication | 2002 |
| Agile ICT Limited | Information & communication | 2008 |
| Agile ICT Property Holdings Limited | Real estate | 2008 |
| Agility Business Consulting Limited | Professional & scientific | 2021 |
| Agility Financial Planning Ltd | Professional & scientific | 2023 |
| Agri-Business Services (UK) Ltd | Agriculture & fishing | 2003 |
| Agritek Holdings Limited | Financial services | 2021 |
| Agritek Limited | Other services | 1999 |
| Agrotransport Ltd | Wholesale & retail | 2020 |
| Ahag Realisation LLP | | 2024 |
| AHK Security Solutions Ltd | Administrative & support | 2022 |
| Ahprocess Ltd | Public administration | 2023 |
| AIM Netball Academy Ltd | Education | 2023 |
| Aimsilva Limited | Information & communication | 2020 |
| Aimslab Ltd. | Education | 2014 |
| Aimylos Consulting Ltd | Professional & scientific | 2023 |
| Air Improve Limited | Construction | 1998 |
| Aire Communications Ltd | Professional & scientific | 2023 |
| Airfleet Solutions Ltd | Administrative & support | 2025 |
| Airlie Lane Property Company Limited | Hospitality | 1997 |
| Airlie Road (Residents) Management Company Limited | Households | 1994 |
| Airlynx Cruise Parking Limited | Transport & logistics | 2024 |
| Airlynx Parking Limited | Professional & scientific | 2013 |
| Airship Limited | Information & communication | 2009 |
| Aistate Management Limited | Professional & scientific | 2025 |
| Aitken Advisory Limited | Financial services | 2023 |
| AJ Statistics Ltd | Professional & scientific | 2018 |
| AJB Gardens Limited | Administrative & support | 2020 |
| AK Transport Ltd | Transport & logistics | 2021 |
| Akaladevi Limited | Hospitality | 2025 |
| Akeera Business Coaching Limited | Professional & scientific | 2011 |
| Akeso Sobriety Ltd | Wholesale & retail | 2023 |
| Akimoto Associates Limited | Professional & scientific | 2002 |
| AL Automotive Limited | Professional & scientific | 2025 |
| Alan Saunders Associates Limited | Administrative & support | 1999 |
| Alan Sherwood Associates Limited | Professional & scientific | 2014 |
| ALB Capital Markets Limited | Financial services | 2023 |
| ALB Management Consultants Limited | Financial services | 2023 |
| Alba Tyres Limited | Extraterritorial | 1985 |
| Albany Apartments Limited | Households | 2000 |
| Albemarle Properties Development Limited | Construction | 2014 |
| Alconex Holdings Limited | Financial services | 2022 |
| Aldus Capital Limited | Professional & scientific | 2020 |
| Alevelbiologytutor Limited | Education | 2018 |
| Aleveltutors.Online Limited | Education | 2022 |
| Alex Smith Guns Ltd | Manufacturing | 2019 |
| Alex White Racing (UAE) Ltd | Information & communication | 2024 |
| Alexander Appliances Direct Ltd | Administrative & support | 2006 |
| Alexander Commerce Limited | Wholesale & retail | 2025 |
| Alexander Corrie Ltd | Information & communication | 2011 |
| Alexander Design Limited | Professional & scientific | 1997 |
| Alexandra Sports (Winchester) Limited | Wholesale & retail | 2016 |
| Alexandra Young Design Ltd | Professional & scientific | 2021 |
| Alfa 2015 Ltd. | Professional & scientific | 2015 |
| Alfred Group Holdings Limited | Financial services | 2022 |
| Alfred Homes Developments Limited | Construction | 2021 |
| Alfred Homes Limited | Construction | 2009 |
| Alfred Homes Properties LLP | | 2022 |
| Alfred Investment Properties Limited | Construction | 2022 |
| Alfred Investments LLP | | 2022 |
| Alfred's Brewery Ltd | Extraterritorial | 2011 |
| Alfresco Concepts (UK) Limited | Wholesale & retail | 2010 |
| Alfresco Concepts Holdings Limited | Professional & scientific | 2021 |
| Alice and TIM Bell Ltd | Wholesale & retail | 2026 |
| Aligadro Holdings Ltd | Real estate | 2020 |
| Alison Baker Associates Limited | Professional & scientific | 2017 |
| Alistair Jones Photography Limited | Professional & scientific | 2011 |
| Alium Properties Limited | Real estate | 2016 |
| Alkan Holding Ltd | Financial services | 2023 |
| ALL Data Consulting Limited | Information & communication | 2023 |
| ALL Trade Windows Limited | Wholesale & retail | 2006 |
| Allbrook Heating Limited | Construction | 2012 |
| Almighty Shine Ltd | Administrative & support | 2019 |
| Alniro Limited | Information & communication | 2007 |
| Aloenterprises Limited | Wholesale & retail | 2007 |
| Alongside Marine Ltd. | Professional & scientific | 2007 |
| Alpha Fitness Hampshire Limited | Arts & recreation | 2020 |
| Alpha Mike Ltd | Hospitality | 2025 |
| Alpha Omega Pathology Ltd | Health & social care | 2018 |
| Alphaveata Ltd | Other services | 2024 |
| Alpine Capital Ltd | Financial services | 2018 |
| Alresford Dental Care Limited | Health & social care | 2010 |
| Alsop & Co. Limited | Professional & scientific | 2015 |
| Altajective Limited | Information & communication | 2011 |
| Altemont Asset Management Limited | Construction | 1993 |
| Altered Realty Ltd | Real estate | 2024 |
| Altermead Limited | Extraterritorial | 1991 |
| Alternatech Limited | Manufacturing | 2015 |
| Alternative Capital Strategies Limited Partnership | | 2013 |
| Altiplano Films Limited | Information & communication | 2013 |
| Alton Services Ltd | Administrative & support | 2017 |
| Always Morocco Ltd | Administrative & support | 2018 |