| Alto Living Group Ltd | Administrative & support | 2019 |
| Altonet Ltd. | Information & communication | 2016 |
| Altum Viditur Limited | Information & communication | 2017 |
| Alty Towers Ltd | Real estate | 2022 |
| Alucorb Limited | Other services | 2016 |
| Alvalade Ltd | Other services | 2025 |
| ALW Ventures Ltd | Real estate | 2025 |
| Always Off-Season Limited | Wholesale & retail | 2025 |
| Alyson Hollway Psychology Limited | Professional & scientific | 2019 |
| AM & RS Capital Ltd | Financial services | 2021 |
| AM & RS Holdings Ltd | Real estate | 2020 |
| AM & RS Investments Ltd | Real estate | 2021 |
| AM & RS Ventures Ltd | Real estate | 2021 |
| AM Anaesthetics Limited | Health & social care | 2022 |
| AM Consultancy Projects Limited | Professional & scientific | 2012 |
| AM Estates 1 Ltd | Real estate | 2025 |
| AM Estates Accrington Ltd | Real estate | 2023 |
| AM Estates Bangor Ltd | Real estate | 2023 |
| AM Estates MCR Ltd | Real estate | 2022 |
| AM Estates NW Ltd | Real estate | 2023 |
| AM Joinery (MCR) Limited | Construction | 2013 |
| AM Lifts Ltd | Construction | 2026 |
| AM Lister Limited | Real estate | 1957 |
| AM Properties Ltd | Real estate | 2013 |
| AM Social Work Limited | Health & social care | 2025 |
| AM Technology Solutions Limited | Professional & scientific | 2010 |
| AM1 Developments Ltd | Real estate | 2024 |
| AM7 Solutions Ltd | Wholesale & retail | 2026 |
| Amaa Property Limited | Real estate | 2024 |
| Amaani Online Ltd | Wholesale & retail | 2025 |
| Amae Properties Limited | Real estate | 2015 |
| Amanda Grundy Consultancy Limited | Professional & scientific | 2021 |
| Amanda Pierce Aesthetics Ltd | Other services | 2011 |
| Amara IQ Ltd | Hospitality | 2023 |
| Amark Windows Limited | Construction | 2002 |
| Amaven Limited | Education | 2014 |
| Amazing Property Solution Ltd | Real estate | 2023 |
| Amazing Voyages Limited | Administrative & support | 2008 |
| AMB Care Ltd | Administrative & support | 2017 |
| AMB Holdings Limited | Professional & scientific | 2003 |
| AMB Lifting Services Limited | Construction | 2019 |
| AMB Personnel Limited | Administrative & support | 2023 |
| AMB Real Estate Limited | Real estate | 2021 |
| AMB Recruitment Group Limited | Administrative & support | 2007 |
| Amber a Property Investments Ltd | Real estate | 2024 |
| Amber Fire Protection Services Ltd | Other services | 2003 |
| Amber Lighting Ltd | Information & communication | 2026 |
| Amber Rose Hair Ltd | Other services | 2024 |
| Amber-Rose Mccann Ltd | Administrative & support | 2024 |
| Amberscaff Ltd | Construction | 2018 |
| Ambiance Care Limited | Health & social care | 2020 |
| Ambisie Limited | Professional & scientific | 2015 |
| Ambit Architectural Design Ltd | Professional & scientific | 2010 |
| Ambrconnect Limited | Professional & scientific | 2026 |
| AMC Interactive Limited | Administrative & support | 2015 |
| AMC Orthodontics Ltd | Administrative & support | 2017 |
| AMC Residential Ltd | Real estate | 2018 |
| AMD Automotive Limited | Wholesale & retail | 2016 |
| AMD Exhibitions Limited | Professional & scientific | 2008 |
| Amec NW Ltd | Construction | 2023 |
| Ameliora Limited | Professional & scientific | 2006 |
| Amer Medical Ltd | Health & social care | 2026 |
| Amethi Vets Ltd | Professional & scientific | 2023 |
| AMF Realty Ltd | Real estate | 2021 |
| Amfrey Properties Limited | Real estate | 2022 |
| AMG Gemini Investments Limited | Real estate | 2017 |
| AMG Writing Ltd | Administrative & support | 2022 |
| AMH Consumer Group Ltd. | Professional & scientific | 2019 |
| AMH Consumer Limited | Professional & scientific | 2024 |
| Amici (Bramhall) Limited | Hospitality | 2023 |
| Amicus Recruitment Holdings Limited | Administrative & support | 2020 |
| Amicus Recruitment Limited | Administrative & support | 2016 |
| Amie Reece Ltd | Professional & scientific | 2025 |
| Amin Car Sales Ltd | Wholesale & retail | 2019 |
| Amin Feasto Ltd | Hospitality | 2025 |
| Amin Musa Ltd | Professional & scientific | 2022 |
| Amity Digital Commerce Ltd. | Professional & scientific | 2011 |
| AMJ Civils Limited | Construction | 2022 |
| Amjad Crown Commerce Ltd | Wholesale & retail | 2026 |
| AMK Corporate Services Limited | Administrative & support | 2018 |
| AMK Projects Limited | Professional & scientific | 1996 |
| AMM Consultants Limited | Professional & scientific | 2017 |
| Ammar & Co (UK) Ltd | Construction | 2019 |
| Ammar Corporation Limited | Construction | 2020 |
| Ammar&Yasser Limited | Health & social care | 2026 |
| Ammerud Fysioterapi Limited | Administrative & support | 2007 |
| Ammluk Ltd | Health & social care | 2013 |
| Ammonite Consulting Limited | Information & communication | 1998 |
| Amol Enterprises Ltd | Manufacturing | 2017 |
| Amore Cafe Limited | Hospitality | 2025 |
| Amoretti LLP | | 2008 |
| Amour Padel Ltd | Arts & recreation | 2025 |
| AMP 75 Limited | Administrative & support | 1975 |
| AMP Asset Solutions Ltd | Education | 2021 |
| AMP# Project Engineering Services Ltd | Professional & scientific | 2025 |
| Ampersand Salons Limited | Other services | 2018 |
| Ampirski Ltd | Health & social care | 2021 |
| Ample Building Solutions Limited | Construction | 2019 |
| Ample Conductor Electrical Services Limited | Construction | 2011 |
| Ampleforth House Management Company (Warrington) Limited | Households | 2004 |