| Alice Springs Limited | Other services | 2019 |
| Aliera Ltd | Professional & scientific | 2014 |
| Align Management Solutions Ltd | Information & communication | 2023 |
| Aligned Mindset Therapy Limited | Education | 2016 |
| Aligned Wellness Academy Ltd | Health & social care | 2022 |
| Alimatt Ltd | Real estate | 2019 |
| Alin Vacaru Limited | Construction | 2017 |
| Aljazi Ltd | Extraterritorial | 2023 |
| Alkemy Investments Limited | Real estate | 2015 |
| Alkemy Solutions Limited | Real estate | 2015 |
| ALL About Kids Therapy Limited | Health & social care | 2026 |
| ALL Car Needs Ltd | Wholesale & retail | 2011 |
| ALL Clear Plumbing Limited | Construction | 2025 |
| ALL Day Plumb Limited | Wholesale & retail | 2018 |
| ALL in One Renovation Ltd | Construction | 2023 |
| ALL the AS Ltd | Real estate | 2024 |
| Allardice Property Limited | Real estate | 2020 |
| Allday Lamps Limited | Wholesale & retail | 2005 |
| Allsgood Capital Ltd | Wholesale & retail | 2025 |
| Allstock Counsulting Limited | Financial services | 2014 |
| Almida Mazuru Limited | Real estate | 2023 |
| Alor Healthcare Limited | Health & social care | 2025 |
| Alperton Fruit and VEG Ltd | Wholesale & retail | 2025 |
| Alpha Dealership Limited | Wholesale & retail | 2024 |
| Alpha Indus Limited | Wholesale & retail | 2021 |
| Alpha Marketing Consultancy Limited | Other services | 2016 |
| Alpha Shipping Ltd | Transport & logistics | 2008 |
| Alphaa Life Ltd | Real estate | 2024 |
| Alphacentrix Ltd | Information & communication | 2026 |
| Alphaimmersia Ltd | Information & communication | 2024 |
| Alpharomeo Limited | Real estate | 2020 |
| Alpine Group Investments Limited | Manufacturing | 2012 |
| Alrisa Limited | Real estate | 2025 |
| Alternatepress Limited | Information & communication | 2012 |
| Alternative Energy Group Ltd | Professional & scientific | 2021 |
| Altham Road Management Company Limited | Other services | 2005 |
| Altima Limited | Wholesale & retail | 2026 |
| Altitude Group Investments Limited | Professional & scientific | 2023 |
| Alts Medical Limited | Health & social care | 2026 |
| Alveston Fine Arts Ltd | Wholesale & retail | 2016 |
| ALW2002 Ltd | Other services | 2025 |
| Alwayson Funding Limited | Financial services | 2026 |
| AM Coffee Retail Limited | Hospitality | 2013 |
| AM Properties Investment Ltd | Households | 2018 |
| AM. Waste (London) Limited | Water & waste | 2004 |
| AMA Consultancy Services Limited | Professional & scientific | 2023 |
| Amaani International Ltd | Wholesale & retail | 2021 |
| Amai Vedanta Limited | Professional & scientific | 2014 |
| Amak Properties Limited | Real estate | 2020 |
| Amalfi Investment Group Ltd | Wholesale & retail | 2017 |
| Amalgamated Incorporated Limited | Professional & scientific | 2019 |
| Amatsu Therapy International (UK) Limited | Other services | 2015 |
| Amazed Buy and Sell Limited | Other services | 2024 |
| Amazing Carpets Ltd | Wholesale & retail | 2018 |
| Amazon Public Relations Limited | Administrative & support | 2000 |
| AMB Property (Northwood) Limited | Construction | 2016 |
| AMB Property Ltd | Real estate | 2010 |
| AMB Psychiatry Limited | Health & social care | 2022 |
| Ambalex Ltd | Professional & scientific | 2025 |
| Ambee Trading Limited | Wholesale & retail | 2011 |
| Amber Cars Limited | Transport & logistics | 1999 |
| Amber Green Solutions Ltd | Administrative & support | 2019 |
| Amber Management Limited | Information & communication | 1993 |
| Ambis Consulting Limited | Professional & scientific | 2026 |
| Ambresbury Limited | Construction | 2014 |
| Ambros Direct (UK) Limited | Wholesale & retail | 1996 |
| Ambros Home Ltd | Wholesale & retail | 2024 |
| Ambros Invest Ltd | Hospitality | 2022 |
| Amcat Consulting Limited | Professional & scientific | 2019 |
| Amelia Nallamilli Limited | Professional & scientific | 2012 |
| Amersham Technology Limited | Financial services | 2007 |
| Amesjo Ltd | Real estate | 2021 |
| Amey Commercial Ltd | Administrative & support | 2018 |
| AMG Painting & Decorating Ltd | Construction | 2019 |
| Amid Construct Ltd | Other services | 2018 |
| Aminwholesalers Ltd | Wholesale & retail | 2024 |
| Amjada Ltd | Information & communication | 2021 |
| Amjas Consulting Limited | Wholesale & retail | 2024 |
| Amkop Limited | Professional & scientific | 2019 |
| AML Group Holdings Ltd | Financial services | 2025 |
| Amlani Medical Ltd | Health & social care | 2022 |
| Ammg Ltd | Real estate | 2021 |
| Ammonite Events Ltd | Administrative & support | 2021 |
| Amom Ltd | Wholesale & retail | 2025 |
| Amor Estates Limited | Real estate | 2019 |
| Amor Investments Ltd | Construction | 2014 |
| Amore Health Ltd | Professional & scientific | 2007 |
| AMP Practices Limited | Health & social care | 2019 |
| Amprias Ltd | Real estate | 2022 |
| Amps Investment Ltd | Real estate | 2024 |
| Amrit 4 Constructions Limited | Construction | 2013 |
| Amro Commercial Real Estate Ltd | Real estate | 2011 |
| AMS Property Ventures Limited | Real estate | 2018 |
| Amsik Kangley Limited | Real estate | 2004 |
| Amsik Limited | Real estate | 1989 |
| Amsik Property Limited | Extraterritorial | 1999 |
| Amsik Sydenham Limited | Real estate | 2023 |
| Amsik Thurrock Limited | Real estate | 2001 |
| Amsti Limited | Hospitality | 1988 |
| Amvaa Ltd | Health & social care | 2021 |