| Advanced Vehicle Concepts Limited | Manufacturing | 2004 |
| Advanced Well-Being Ltd | Administrative & support | 2023 |
| Advanced Wellness Spa Ltd. | Other services | 2019 |
| Advancium I.T. Ltd | Information & communication | 2014 |
| Advantage Global Ltd | Information & communication | 2025 |
| Advantage Global Positioning Limited | Professional & scientific | 2008 |
| Advantage Marketing Corporation Limited | Administrative & support | 1997 |
| Adventico Ltd | Information & communication | 2020 |
| Adventure Cycle Hire Ltd | Other services | 2019 |
| Adventure Cycle Hire RP Ltd | Other services | 2024 |
| Adventure Farm Day Nursery Ltd | Education | 2020 |
| Advertiser and Times Limited | Real estate | 2012 |
| Adverttu Limited | Professional & scientific | 2015 |
| Advex Ltd | Other services | 2020 |
| Adviser Insight Limited | Information & communication | 2024 |
| Advita Academy Ltd | Professional & scientific | 2025 |
| Adviti Ltd | Information & communication | 2020 |
| Adwoa Corp Ltd | Wholesale & retail | 2022 |
| ADY Brickwork Limited | Construction | 2017 |
| Adyah Limited | Real estate | 2023 |
| Adypt Group Limited | Information & communication | 2020 |
| Adypt Limited | Information & communication | 2015 |
| ADZ Plumbing and Heating Ltd | Construction | 2026 |
| AE Garden Rooms Ltd | Construction | 2025 |
| AE Steel Co Ltd | Wholesale & retail | 2021 |
| AEC Independent Ltd | Administrative & support | 2014 |
| Aecm Nominees Limited | Financial services | 2020 |
| Aecoplan Integrated Project Services Ltd | Administrative & support | 2023 |
| Aecoplan Limited | Administrative & support | 2014 |
| Aedifex.Build Ltd | Construction | 2025 |
| Aeec Equipment Limited | Manufacturing | 2025 |
| AEG Care Limited | Health & social care | 2014 |
| Aegeria Procurement Ltd | Administrative & support | 2019 |
| Aegis Telecom Limited | Information & communication | 2018 |
| Aeism Agency Limited | Professional & scientific | 2020 |
| Aelita Ltd | Wholesale & retail | 2018 |
| AEM Plumbing & Heating Limited | Other services | 2022 |
| Aenos Solutions Ltd | Professional & scientific | 2019 |
| AEO Business Consulting Ltd | Information & communication | 2016 |
| Aeon UK Limited | Extraterritorial | 2005 |
| AER 4 Couriers Ltd | Transport & logistics | 2024 |
| Aero Express Aviation Limited | Manufacturing | 2010 |
| Aero Media Ltd | Information & communication | 2024 |
| Aero TEC Laboratories Limited | Manufacturing | 1998 |
| Aero-Race-Tech Ltd | Transport & logistics | 2008 |
| Aerojobs Services Limited | Professional & scientific | 2009 |
| Aeromtb Ltd | Administrative & support | 2024 |
| Aeroponic Ltd | Other services | 2024 |
| Aerosoft Technologies Ltd | Information & communication | 2024 |
| Aerospace Design Limited | Professional & scientific | 2000 |
| Aerothermal Limited | Manufacturing | 2006 |
| Aerotrix Labs Ltd | Information & communication | 2023 |
| Aesclepius Consulting Limited | Professional & scientific | 2006 |
| Aesir Technologies UK Limited | Extraterritorial | 2021 |
| Aesthetics by HC Ltd | Health & social care | 2022 |
| Aether UKI Ltd | Information & communication | 2025 |
| AEX Recruitment Ltd | Administrative & support | 2021 |
| AF Architecture Ltd | Professional & scientific | 2026 |
| AF Funding Limited | Financial services | 2025 |
| AF Property Developments Limited | Real estate | 2024 |
| AF Trading Limited | Other services | 2007 |
| AFA Trading Ltd | Wholesale & retail | 2018 |
| Afahah Ltd | Wholesale & retail | 2014 |
| Afath GP Medical Ltd | Health & social care | 2021 |
| AFC Domestic Services Ltd | Professional & scientific | 2023 |
| AFC Dunstable Football Limited | Arts & recreation | 2023 |
| AFC Group Ltd | Construction | 2016 |
| Afex Agentes DE Valores Ltd | Administrative & support | 2022 |
| Affable Properties Limited | Real estate | 2018 |
| Affinitas Bidco Limited | Financial services | 2021 |
| Affinitas Midco Limited | Financial services | 2021 |
| Affinitas Spain Holdco 2 Limited | Financial services | 2023 |
| Affinitas Spain Holdco Limited | Financial services | 2022 |
| Affinitas Topco Limited | Financial services | 2021 |
| Affinity Consultancy Management Ltd | Professional & scientific | 2012 |
| Affirm IT Limited | Information & communication | 2010 |
| Affirmative Consulting Limited | Other services | 2019 |
| Affordable Homes Partnership Ltd | Professional & scientific | 2023 |
| AFG Investco Ltd | Real estate | 2024 |
| Afgl Ltd | Real estate | 2017 |
| AFL Telecommunications Holdings UK Limited | Professional & scientific | 2006 |
| AFL Telecommunications UK Limited | Wholesale & retail | 1992 |
| Afon Building and Consultancy Services Limited | Households | 2013 |
| Afra-K Ltd | Wholesale & retail | 2024 |
| Africa Go Solar Ltd | Energy | 2018 |
| Africa Mobile Networks Limited | Information & communication | 2013 |
| Africa Policy Forum Limited | Professional & scientific | 2011 |
| Africa Trade Procurement Limited | Wholesale & retail | 2015 |
| African Caribbean Pacific Diaspora Youth Support Services (Acpdyss) | Education | 2024 |
| African Continental Trading Co. Limited | Hospitality | 2018 |
| African Cultural Heritage Ltd | Hospitality | 2025 |
| African Diaspora Foundation Ltd | Education | 2019 |
| African Wonder Women Organisation CIC | Health & social care | 2022 |
| Africlinix Solutions Ltd | Professional & scientific | 2026 |
| Africonsult Ventures Limited | Other services | 2024 |
| Afsamm Limited | Education | 2021 |
| Afsha Investments Limited | Real estate | 2025 |
| AFW Engineering Services Ltd | Professional & scientific | 2023 |
| AFW Marketing Ltd | Professional & scientific | 2025 |
| AG Business Group Ltd | Wholesale & retail | 2024 |