| AMB Storage Ltd | Other services | 2023 |
| Amba Tools Limited and Partners Plant and Machinery Hire | | 1986 |
| Ambassadors for Christ | Other services | 2012 |
| Amber Care Solutions Ltd | Health & social care | 2023 |
| AMBER365 Limited | Information & communication | 2014 |
| Ambergate Property Management Company Ltd | Real estate | 2021 |
| Ambrose Independent Trading Limited | Transport & logistics | 2025 |
| Amcada Consulting Limited | Information & communication | 2023 |
| AMD Will Writing Services Limited | Administrative & support | 2001 |
| Amenable Care Ltd | Administrative & support | 2022 |
| Amersham Aerial FIX Ltd | Information & communication | 2013 |
| Amersham Heating Limited | Construction | 2007 |
| Amethyst (CME) Limited | Administrative & support | 2006 |
| AMG Roofing (Bucks) Ltd | Construction | 2020 |
| Amicus Construction Limited | Construction | 2017 |
| Amira 13 Limited | Hospitality | 2024 |
| Amirah LDN Ltd | Wholesale & retail | 2022 |
| Amittai LEE Antoine Architects Limited | Professional & scientific | 2023 |
| Amiyaa Ltd | Professional & scientific | 2025 |
| Ammonite Futures Ltd | Health & social care | 2024 |
| Amobi Properties Ltd | Real estate | 2024 |
| Amora Property Limited | Real estate | 2025 |
| Amore Arcade Ltd | Wholesale & retail | 2025 |
| Ample Fordian Services Ltd | Professional & scientific | 2015 |
| Amplified Consulting Limited | Administrative & support | 2018 |
| Ampy Aylesbury Ltd | Professional & scientific | 2025 |
| AMR Flat Roofing Ltd | Construction | 2024 |
| Amroth Consulting Ltd | Information & communication | 2024 |
| Amtek Plumbing and Heating Limited | Construction | 2023 |
| AMY Ellen Ltd | Financial services | 2022 |
| AN Cars Ltd | Wholesale & retail | 2025 |
| ANA Resources Limited | Health & social care | 2016 |
| Anabia Ltd | Health & social care | 2020 |
| Anaclara Systems Limited | Information & communication | 1995 |
| Ananditi Medical Limited | Health & social care | 2019 |
| Anas Raja 1 Limited | Real estate | 2026 |
| Anas Raja Limited | Real estate | 2026 |
| Anchor Meadows Services Limited | Agriculture & fishing | 2026 |
| Anchor Music Ltd | Wholesale & retail | 2024 |
| Anchora Labs Ltd | Information & communication | 2025 |
| Anchorcare Collective Limited | Health & social care | 2025 |
| Andrew Norris Kitchens & Bathrooms Limited | Construction | 2003 |
| Andrew RUT Limited | Professional & scientific | 2024 |
| Andrew Weir Pension Trustee Limited | Financial services | 2011 |
| Andrews Construction Group Limited | Construction | 2025 |
| Andrews Electrics Limited | Manufacturing | 2013 |
| Andy & Nigel Properties Ltd | Real estate | 2023 |
| Andy Boyle Consultancy Limited | Wholesale & retail | 2025 |
| Andy Crompton Ltd | Arts & recreation | 2005 |
| Andy Kemp Tennis Ltd | Arts & recreation | 2009 |
| Andy Small Design & Build Limited | Construction | 2014 |
| Andy Theobald & Sons Ltd | Transport & logistics | 2024 |
| Andyfridge Ltd | Manufacturing | 2023 |
| Aner Group Limited | Construction | 2026 |
| Angel Dash Associates Ltd | Information & communication | 2019 |
| Angell Pinder Limited | Extraterritorial | 2016 |
| Angella Pilates Ltd | Other services | 2021 |
| Angels Care Agency Limited | Administrative & support | 2008 |
| Angels Real Estates Limited | Real estate | 2022 |
| Angels Supports Services Ltd | Health & social care | 2022 |
| Angels Window Cleaning Ltd | Administrative & support | 2025 |
| ANI Sounds Limited | Information & communication | 1999 |
| ANIL4S Limited | Information & communication | 2022 |
| Animal Antiks | Health & social care | 2016 |
| Animal Antiks Holdings Ltd | Real estate | 2025 |
| Animal PUB Company Limited | Hospitality | 2013 |
| ANIMATE4.COM Ltd. | Information & communication | 1999 |
| Anish Dosani Consulting Ltd | Professional & scientific | 2018 |
| Ankay Consultancy Ltd | Professional & scientific | 2023 |
| Ankhai Limited | Wholesale & retail | 2024 |
| Ankurit Limited | Financial services | 2017 |
| ANN Martine Ltd | Wholesale & retail | 2020 |
| Anna Mackie Ltd | Professional & scientific | 2017 |
| Annabel Harrison Ltd | Arts & recreation | 2018 |
| Annie Harrington Ltd | Wholesale & retail | 2013 |
| Annomando Ltd | Financial services | 2008 |
| Anpr Parking Services Ltd | Administrative & support | 2013 |
| Anstech Services Ltd | Information & communication | 2024 |
| ANT and Honey Engineering Ltd | Construction | 2019 |
| Anti Ceci Wisdom Food Ltd | Hospitality | 2022 |
| Anton's Ice Cream Limited | Hospitality | 2026 |
| Anura Sanctuary Limited | Information & communication | 2026 |
| Anvita Infotech Limited | Information & communication | 2015 |
| Anya Technology Services Limited | Hospitality | 2018 |
| Anyauto Part Limited | Wholesale & retail | 2017 |
| AOT Tyres & Servicing Ltd | Wholesale & retail | 2025 |
| AOT Waste Removal Ltd | Administrative & support | 2024 |
| AP Building Restorations Ltd | Construction | 2022 |
| AP Willows Property Management Ltd | Real estate | 2025 |
| Apartments on the Piste Ltd | Real estate | 2014 |
| APC 23 Ltd | Professional & scientific | 2016 |
| Apem Components Limited | Manufacturing | 1983 |
| Aperture Digital Media Ltd | Information & communication | 2012 |
| Apex Accounts Ltd | Professional & scientific | 2023 |
| Apex Auto Consultants Limited | Professional & scientific | 2025 |
| Apex BRS Limited | Construction | 2024 |
| Apex Co Properties Ltd | Real estate | 2025 |
| Apex Finance Limited | Financial services | 1999 |
| Apex Kakumanu Ltd | Information & communication | 2014 |
| APH Pools Ltd | Administrative & support | 2024 |