| Alpha (S & P) Holdings Limited | Professional & scientific | 2024 |
| Alpha Accountancy & Management Services 24 Ltd | Professional & scientific | 2024 |
| Alpha Acquisitions (UK) Limited | Professional & scientific | 2006 |
| Alpha Ariel Solutions Limited | Information & communication | 2014 |
| Alpha Business Management Limited | Professional & scientific | 2014 |
| Alpha CC Limited | Professional & scientific | 2018 |
| Alpha Control Services Ltd | Manufacturing | 2002 |
| Alpha Crucis Solutions Ltd | Professional & scientific | 2019 |
| Alpha Decal & Nameplate Company Ltd | Manufacturing | 2001 |
| Alpha Executive Search LLP | | 2005 |
| Alpha FNB Ltd | Hospitality | 2024 |
| Alpha Immobile Limited | Professional & scientific | 2003 |
| Alpha Juliet Properties Ltd | Real estate | 2023 |
| Alpha Mark Communications Limited | Wholesale & retail | 1995 |
| Alpha ME Ltd | Manufacturing | 2023 |
| Alpha Portfolio Management Ltd | Extraterritorial | 2017 |
| Alpha Precision Limited | Construction | 2022 |
| Alpha RAT Ltd | Professional & scientific | 2014 |
| Alpha Seven Group Holdings Limited | Households | 2026 |
| Alpha Seven Property Management Ltd | Real estate | 2026 |
| Alpha Solutions U.K Ltd | Health & social care | 2015 |
| Alpha Trading Group NE Ltd | Financial services | 2019 |
| Alpha Wastewater Services Limited | Water & waste | 2016 |
| Alpha-Zeta Abseiling Limited | Professional & scientific | 2015 |
| Alphabet Childcare Ltd | Extraterritorial | 2013 |
| Alphabet Communications Limited | Professional & scientific | 2017 |
| Alphabet Gym Ltd | Arts & recreation | 2017 |
| Alphabet Moon Publishing Limited | Information & communication | 2022 |
| Alphanova Ltd | Professional & scientific | 2010 |
| Alphapet Management Services Limited | Extraterritorial | 2011 |
| Alphard Engineering Ltd | Construction | 2024 |
| Alphatotas Limited | Construction | 2010 |
| Alphonsa Blinds Limited | Wholesale & retail | 2024 |
| Alpina Property Consultancy Limited | Professional & scientific | 2013 |
| Alpine Air Mountain Training Limited | Administrative & support | 2013 |
| Alpine Autos Limited | | 1988 |
| Alpine Business Consulting Limited | Administrative & support | 2010 |
| Alpine Home Maintenance Ltd | Construction | 2026 |
| Alpine Park Homes Ltd | Manufacturing | 2021 |
| Alpine Property Services Limited | Construction | 2014 |
| Alpinum Systems Ltd | Professional & scientific | 2016 |
| Alpinum Training Ltd | Education | 2023 |
| Alpizzeria Food Ltd | Hospitality | 2024 |
| Alqami Limited | Information & communication | 2019 |
| Alqaswah Multiservices Ltd. | Administrative & support | 2018 |
| Alrehmat Foods Limited | Hospitality | 2020 |
| ALS Global Search Ltd | Administrative & support | 2023 |
| ALS Recruiting Limited | Administrative & support | 2015 |
| Alsagai Ltd | Transport & logistics | 2023 |
| Alsaleh Ltd | Health & social care | 2025 |
| Alsius Cooling Limited | Construction | 2012 |
| Also Known AS Art Ltd | Wholesale & retail | 2022 |
| Also UK and Emerging Markets Ltd. | Manufacturing | 2025 |
| Alsr Ltd | Information & communication | 2026 |
| Alstan Travel Ltd | Administrative & support | 2025 |
| Alsurpal Ltd | Professional & scientific | 2026 |
| ALT Developments Limited | Construction | 2021 |
| ALT Holding Investments Limited | Professional & scientific | 2016 |
| ALT Key Ltd | Information & communication | 2023 |
| ALT Properties Bristol Ltd | Real estate | 2026 |
| Alta Loma Ltd | Hospitality | 2024 |
| Alta Volare Ltd | Transport & logistics | 2021 |
| Altacontrols Limited | Information & communication | 2024 |
| Altadis Newco Limited | Financial services | 2019 |
| Altaroute Limited | Manufacturing | 1978 |
| Altcare Ltd | Health & social care | 2024 |
| Alte Solutions Limited | Professional & scientific | 2015 |
| Altec Professional Consultancy Services Limited | Professional & scientific | 2018 |
| Altera Production UK Limited | Mining & quarrying | 1995 |
| Alteration Station Ltd | Other services | 2016 |
| Altered Carbon Limited | Professional & scientific | 2018 |
| Alteriors Design and Build Ltd | Construction | 2020 |
| ALTERN8 Limited | Information & communication | 1998 |
| Alternate Electrical Services Limited | Manufacturing | 2014 |
| Alternative Advertising Limited | Professional & scientific | 2002 |
| Alternative Business Funding Limited | Information & communication | 2014 |
| Alternative Pathways Education Ltd | Education | 2024 |
| Altero Eyewear Ltd | Wholesale & retail | 2026 |
| Altitube Scaffolding Ltd | Construction | 2021 |
| Altitude Labs Limited | Information & communication | 2021 |
| Altlantic Design Limited | Professional & scientific | 2009 |
| Altlign Ltd | Administrative & support | 2026 |
| Alto Homes Design Limited | Real estate | 2026 |
| Alto Inc Ltd | Wholesale & retail | 2024 |
| Altogether Procurement Limited | Administrative & support | 2025 |
| Alton Autos Ltd | Extraterritorial | 2023 |
| Alton Bidco Limited | Financial services | 2025 |
| Alton Electrical Services (South West) Ltd | Construction | 2016 |
| Alton Holdco Limited | Financial services | 2025 |
| Alton Wealth Management Limited | Financial services | 2017 |
| Altonian Coaches Ltd | Transport & logistics | 2004 |
| Altosi Ltd | Wholesale & retail | 2008 |
| Altrin Systems Technology Ltd | Wholesale & retail | 2022 |
| Altrix Labs Limited | Information & communication | 2024 |
| Altt Productions Limited | Information & communication | 2024 |
| Altu Holding Limited | Information & communication | 2016 |
| Altu Technology Limited | Manufacturing | 2016 |
| Altum Designs Ltd | Manufacturing | 2015 |
| Altura English Ltd | Education | 2025 |
| Alturis Health Limited | Information & communication | 2021 |