| Alpha 1 Security Solutions Limited | Construction | 2009 |
| Alpha Dynamic Ventures Ltd | Manufacturing | 2018 |
| Alpha Electrical Contractors (Chesterfield) Ltd | Construction | 2019 |
| Alpha Heating (Chesterfield) Limited | Construction | 2002 |
| Alpha Independent Financial Solutions Limited | Financial services | 2013 |
| Alpha Leonis Group Limited | Professional & scientific | 2020 |
| Alpha Plant Hire Limited | Real estate | 1987 |
| Alpha Plant Holdings Limited | Financial services | 2017 |
| Alphagen Group Ltd | Extraterritorial | 2023 |
| Alphagen Ltd | Manufacturing | 2023 |
| Alphagen Systems Limited | Construction | 2024 |
| ALT Rubber & Plastics Limited | Manufacturing | 2025 |
| Altek Europe Holdings Limited | Professional & scientific | 2012 |
| Altek Europe Limited | Manufacturing | 2007 |
| Alter EGO Lashes Ltd | Wholesale & retail | 2018 |
| Altida Limited | Manufacturing | 2014 |
| Altitude Media Ltd | Professional & scientific | 2015 |
| Altius Recruitment Ltd | Administrative & support | 2021 |
| Altofts Acres (Wakefield) Management Company Limited | Households | 2025 |
| Alton Detailing Limited | Professional & scientific | 2007 |
| Alton Medical Limited | Health & social care | 2020 |
| Altravision Security Systems Limited | Wholesale & retail | 2016 |
| Alufusion Systems Limited | Manufacturing | 2025 |
| Alvis Register Limited | Other services | 2001 |
| Alya Pizza Ltd | Hospitality | 2022 |
| AM Cleaners UK Ltd | Administrative & support | 2024 |
| AM Pilates Ltd | Health & social care | 2026 |
| Amans Consulting Ltd | Information & communication | 2020 |
| Amara Soft Solutions Ltd | Information & communication | 2022 |
| Amazing Garden Rooms Ltd | Construction | 2023 |
| Amazing Grace Groceries Ltd | Wholesale & retail | 2025 |
| Amazing Grace Solutions Ltd | Health & social care | 2019 |
| AMB Studios Limited | Administrative & support | 2024 |
| Ambassador Auto Ltd | Transport & logistics | 2020 |
| Amber Group Holdings Limited | Financial services | 2017 |
| Amber Plastics Holdings Limited | Professional & scientific | 2015 |
| Amber Spire Limited | Wholesale & retail | 2022 |
| Ambervale Innovation Ltd | Wholesale & retail | 2024 |
| Ambervale Investments Ltd | Construction | 2024 |
| Ambervale Residents Association Limited | Real estate | 1985 |
| Ambi Property Partnership Limited | Real estate | 2023 |
| Ambimedia Ltd | Manufacturing | 2019 |
| Amblers Endoscopy Ltd | Health & social care | 2024 |
| Ambush Paintball Games Limited | Arts & recreation | 1990 |
| Amer Rental Limited | Real estate | 2009 |
| AMF (UK) Limited | Professional & scientific | 2012 |
| Amica Potential Ltd | Professional & scientific | 2025 |
| Amici Ltd | Hospitality | 2026 |
| Amies Innovation Limited | Administrative & support | 2010 |
| Amigo Talent Limited | Administrative & support | 2010 |
| Amigo Therapy Limited | Health & social care | 2024 |
| AMJ Property & Investment Ltd | Real estate | 2017 |
| Amjyo Pathsurge Limited | Health & social care | 2016 |
| AMN Commericals Ltd | Wholesale & retail | 2021 |
| Amok Studio Ltd | Other services | 2024 |
| Amphi Solutions Ltd | Information & communication | 2024 |
| Ampm Property Maintenance Ltd | Construction | 2021 |
| Amrun Group Limited | Wholesale & retail | 2020 |
| AMS Assets Ltd | Real estate | 2024 |
| AMS Prestige Limited | Wholesale & retail | 2010 |
| Amsco (188) Limited | Real estate | 1995 |
| AMY Booth Models Ltd | Wholesale & retail | 2023 |
| AMY FLO Face Painting Ltd | Arts & recreation | 2025 |
| AN Active Life Ltd | Health & social care | 2019 |
| AN House Limited | Real estate | 2024 |
| An-Vision UK Limited | Wholesale & retail | 2023 |
| ANA Energy Ltd | Professional & scientific | 2025 |
| Anavio Consulting Limited | Professional & scientific | 2011 |
| Anchor (Tavern) Limited | Real estate | 2025 |
| Anchor Point Ltd | Wholesale & retail | 2009 |
| Anchor Refractories Limited | Wholesale & retail | 2003 |
| Anchortec Limited | Manufacturing | 2001 |
| Andalusian Horse Direct Ltd | Wholesale & retail | 2016 |
| Andaway Limited | Professional & scientific | 2024 |
| Ander Technologies (Europe) Limited | Manufacturing | 2016 |
| Anderson Consulting Technical Services Ltd | Construction | 2019 |
| Anderson Tree Care Limited | Agriculture & fishing | 2006 |
| Andofam Holdings Limited | Financial services | 2024 |
| Andrew Eric Thacker Unlimited | Extraterritorial | 2025 |
| Andrew Herring & Co Limited | Professional & scientific | 2018 |
| Andrew Marsden Construction Limited | Construction | 2024 |
| Andrew Marsden Financial Services Limited | Professional & scientific | 2014 |
| Andrews Mcandrew Ltd | Real estate | 2022 |
| Andy Brunt Contractor Training Services Ltd | Education | 2019 |
| Angel Heights Scaffolding Ltd | Construction | 2018 |
| Angel Homebrew Ltd | Wholesale & retail | 2022 |
| Angel House Property Developments Limited | Real estate | 2023 |
| Angel Shipping Solutions Limited | Transport & logistics | 2023 |
| Angel Spa Ltd | Other services | 2024 |
| Angelfield Developments Limited | Construction | 2016 |
| Angelfield Property Limited | Real estate | 2018 |
| Angelic, Nails, Beauty &Inner Health Limited | Other services | 2018 |
| Angelimi Care Service Ltd | Health & social care | 2025 |
| Angelsec Limited | Administrative & support | 2018 |
| Angling Lines Ltd | Administrative & support | 2000 |
| Anglo Business Services Limited | Transport & logistics | 2000 |
| ANH Training Limited | Professional & scientific | 2011 |
| ANI Cabs Ltd | Transport & logistics | 2024 |
| ANI Motors Ltd | Wholesale & retail | 2016 |
| Animo Cloud Ltd | Professional & scientific | 2020 |