| Alter Agency Ltd. | Professional & scientific | 1994 |
| Altiel Limited | Wholesale & retail | 2011 |
| Altin Grill Limited | Hospitality | 2025 |
| Alto-Shaam UK Ltd | Wholesale & retail | 2024 |
| Alton Gate Properties Limited | Real estate | 2019 |
| Altor Employment Limited | Households | 2019 |
| Altor Employment Solicitors Limited | Professional & scientific | 2019 |
| Altrego Ltd | Wholesale & retail | 2018 |
| Alts & Cleaning Express Ltd | Other services | 2024 |
| Altum Capital Partners Limited | Administrative & support | 2014 |
| Alva Consultancy Services Limited | Professional & scientific | 2015 |
| Alvagold Limited | Real estate | 1994 |
| Alveris Limited | Transport & logistics | 2008 |
| Alvio Group Limited | Information & communication | 2026 |
| Always Answer AI Ltd | Information & communication | 2026 |
| Always WIN Limited | Information & communication | 2026 |
| Alwaysdreaming Ltd | Hospitality | 2021 |
| Alwayslogistics Limited | Transport & logistics | 2017 |
| Alwaystechnologies Limited | Information & communication | 2008 |
| Alwaystudios Limited | Information & communication | 2012 |
| Alwis Solutions Ltd | Information & communication | 2018 |
| Alx.Sz Ltd | Wholesale & retail | 2023 |
| Alycall Ltd | Administrative & support | 2024 |
| Alyson Ainsworth Coaching Limited | Administrative & support | 2016 |
| Alzomored Ltd | Information & communication | 2023 |
| AM Devops Limited | Information & communication | 2014 |
| AM Electrical Engineering Ltd | Administrative & support | 2019 |
| AM Electrical London Limited | Construction | 2014 |
| AM Industrials Group Ltd | Manufacturing | 2025 |
| AM JAP Auto & Parts Ltd | Wholesale & retail | 2025 |
| AM Miculi Construction Ltd | Construction | 2021 |
| AM Orthodontics Ltd | Health & social care | 2017 |
| AM Taxi Rental Ltd | Transport & logistics | 2022 |
| Am&D Construction Ltd | Construction | 2019 |
| Am&Shah Traders Limited | Wholesale & retail | 2025 |
| AM10 Group Ltd | Real estate | 2025 |
| AM10 Retail Ltd | Other services | 2025 |
| AMA I Transport Ltd | Transport & logistics | 2026 |
| Amac Electrical Limited | Construction | 2016 |
| Amadeus Acoustic Solutions Limited | Other services | 1999 |
| Amadeus Design Furniture Limited | Manufacturing | 2002 |
| Amadeus Design Limited | Manufacturing | 2017 |
| Amadeus Performance Equipment Limited | Wholesale & retail | 1994 |
| Amafella Limited | Wholesale & retail | 2025 |
| Amagiera Ltd | Administrative & support | 2023 |
| Amakit Ltd | Information & communication | 2024 |
| Amalfi Tile Studio Limited | Other services | 2012 |
| Amalkali Healthcare Limited | Health & social care | 2021 |
| Amanah AIK Limited | Real estate | 2025 |
| Amanat International Ltd | Information & communication | 2015 |
| Amanchiahene Enterprise Ltd | Wholesale & retail | 2021 |
| Amanda and Daughters Limited | Health & social care | 2015 |
| Amandla HV Services Limited | Professional & scientific | 2026 |
| Amaravathi Limited | Information & communication | 2016 |
| Amarco Properties Ltd | Real estate | 2021 |
| Amari Financials Limited | Professional & scientific | 2025 |
| Amaria HB Ltd | Construction | 2011 |
| Amariya Ltd | Transport & logistics | 2021 |
| Amarksoft Ltd | Information & communication | 2026 |
| Amarteys Family Group Ltd | Hospitality | 2021 |
| Amasci Creative Limited | Information & communication | 2008 |
| Amaura Limited | Manufacturing | 2020 |
| Amaxa Motors Limited | Wholesale & retail | 2025 |
| AMB Marketing Limited | Professional & scientific | 2022 |
| Ambassador Financial Services Limited | Financial services | 2013 |
| Amber Cuisine Ltd | Hospitality | 2019 |
| Amber Global Finance Limited | Professional & scientific | 2020 |
| Amber Legal Translation and Concierge Services Ltd | Hospitality | 2019 |
| Amberon Limited | Financial services | 2024 |
| Amberwick Trading Limited | Wholesale & retail | 2025 |
| Amberwood Management Company Limited | Households | 1993 |
| Amberzin Global Services Ltd | Health & social care | 2022 |
| Ambient Production Services Limited | Professional & scientific | 2023 |
| Ambika Medicare Ltd | Health & social care | 2023 |
| Ambitian Ltd | Wholesale & retail | 2025 |
| Ambleside (Beechwood Care) Limited | Health & social care | 2025 |
| Ambleside (Complex Care ) Limited | Health & social care | 2025 |
| Ambr Property Investments Ltd | Real estate | 2024 |
| Ambuja Investments Ltd | Real estate | 2021 |
| Ambulance Automotive & Mechanical Services Ltd | Wholesale & retail | 2014 |
| AMC Car Wash Ltd | Wholesale & retail | 2026 |
| AMC Evergreen Ltd | Health & social care | 2017 |
| AMC Finance Management Limited | Professional & scientific | 2020 |
| AMC Rentals Ltd | Real estate | 2025 |
| AMC Tree Services Limited | Administrative & support | 2014 |
| Amcey Energy Ltd | Extraterritorial | 2020 |
| Amco Flooring Limited | Wholesale & retail | 1998 |
| Amcs (Europe) Ltd | Professional & scientific | 2018 |
| AMD Care Services Ltd | Health & social care | 2022 |
| AMD Legal Limited | Other services | 2023 |
| Amdosoft Systems Ltd | Information & communication | 2010 |
| Amec MK Ltd | Construction | 2022 |
| Amedeel Aguta Ltd | Wholesale & retail | 2024 |
| Ameerah Properties 4 U Limited | Real estate | 2020 |
| Amelec Instruments Limited | Manufacturing | 2011 |
| Amelia & Isla Ltd | Financial services | 2024 |
| Ameliespedition Limited | Transport & logistics | 2020 |
| Amelion Fitness Ltd | Arts & recreation | 2025 |
| Amerelia Limited | Information & communication | 2021 |
| American Pacific Computers Limited | Wholesale & retail | 1990 |