| Allassio Clark Developments Limited | Extraterritorial | 2013 |
| Allassio Clark Finance Limited | Professional & scientific | 2023 |
| Allassio Clark Limited | Professional & scientific | 2014 |
| Allcornerspainting Ltd | Construction | 2025 |
| Allcyberone Ltd | Information & communication | 2016 |
| Alldoctors Holdings Ltd | Financial services | 2022 |
| Allegro Mortgages Limited | Financial services | 2018 |
| Allen & Alan Ltd | Construction | 2026 |
| Allen Solution Ltd | Construction | 2018 |
| Alley KAT Ltd | Wholesale & retail | 2019 |
| Allezbeheer Ltd | Other services | 2024 |
| Alliance Francaise DE Milton Keynes | Education | 2003 |
| Alliance Route Logistics Ltd | Transport & logistics | 2026 |
| Allibaba Limited | Agriculture & fishing | 2019 |
| Allied Match Limited | Information & communication | 2025 |
| Allied Portfolio Ltd | Real estate | 2023 |
| Allison European Limited | Transport & logistics | 2015 |
| Allowed Group Limited | Information & communication | 2025 |
| Allowed R&R Limited | Real estate | 2024 |
| Allsopp Avery Partnership Ltd | Construction | 2020 |
| Allsorts Media Ltd | Arts & recreation | 2026 |
| Allspace Cleaners Ltd | Administrative & support | 2024 |
| Allsports Podcast Limited | Information & communication | 2024 |
| Allstargoods Limited | Wholesale & retail | 2023 |
| Alltech Solutions Limited | Administrative & support | 2014 |
| Allure Health & Aesthetics Limited | Health & social care | 2025 |
| Allver Trade Ltd | Wholesale & retail | 2020 |
| Ally Photography Ltd | Information & communication | 2025 |
| Ally Technology Consultancy Limited | Information & communication | 2020 |
| Allyson Williams Care Homes Limited | Health & social care | 2023 |
| Alma Boutique Ltd | Wholesale & retail | 2025 |
| Alma Engineering Co. Limited | Manufacturing | 1982 |
| Alma Home Help Ltd | Health & social care | 2019 |
| Alma Serv Ltd | Extraterritorial | 2019 |
| Almaden Holdings Ltd | Financial services | 2016 |
| Almarco Limited | Professional & scientific | 2022 |
| Almasi Ecotrade Ltd | Water & waste | 2020 |
| Almazaj Limited | Hospitality | 2019 |
| Almina Cafe Ltd | Hospitality | 2019 |
| Almontasereen Group (UK) Limited | Real estate | 2019 |
| Almot Performance Ltd | Wholesale & retail | 2023 |
| Alodia Ltd | Wholesale & retail | 2014 |
| Aloe Accounts Limited | Professional & scientific | 2026 |
| Alogro Holdings Limited | Financial services | 2022 |
| Aloka Green Energy Ltd | Administrative & support | 2023 |
| Aloof HAT Ltd | Information & communication | 2015 |
| Aloysius Fortescue and Smythe (A.F.S.) Ltd | Administrative & support | 2023 |
| Alpaca Evolution Limited | Agriculture & fishing | 2017 |
| Alpcon Limited | Construction | 2012 |
| Alpes Adventures Limited | Hospitality | 2013 |
| Alpha Aerotek Ltd | Administrative & support | 2011 |
| Alpha AID Ltd | Wholesale & retail | 2023 |
| Alpha Bids Limited | Real estate | 2013 |
| Alpha Care Horizon Ltd | Administrative & support | 2024 |
| Alpha Consultant Services Ltd | Construction | 2011 |
| Alpha Design Interiors Limited | Construction | 2007 |
| Alpha Europe Security Limited | Administrative & support | 2026 |
| Alpha Flooring Limited | Wholesale & retail | 2011 |
| Alpha Gamma Beta Ltd | Manufacturing | 2001 |
| Alpha Gemini Ltd | Information & communication | 2026 |
| Alpha Healthcare Holdings Limited | Financial services | 1995 |
| Alpha Horseshoes Limited | Wholesale & retail | 2014 |
| Alpha John Limited | Construction | 2025 |
| Alpha Lifting Solutions Limited | Construction | 2024 |
| Alpha Logistics & Compliance Ltd | Transport & logistics | 2022 |
| Alpha Management Partners Ltd | Real estate | 2025 |
| Alpha Personnel Limited | Administrative & support | 1986 |
| Alpha Plus International Limited | Wholesale & retail | 2005 |
| Alpha Property Holdings Limited | Real estate | 2025 |
| Alpha Steps CIC | Education | 2024 |
| Alpha Tax Accounting Ltd | Professional & scientific | 2025 |
| Alpha Trust International Ltd | Other services | 2010 |
| Alpha UK Services Ltd | Other services | 2024 |
| Alpha Welding and Mechanical Solutions Limited | Manufacturing | 2016 |
| Alphachase Limited | Households | 1987 |
| Alphachem Consulting Ltd | Professional & scientific | 2025 |
| Alphacore Services Limited | Professional & scientific | 2008 |
| Alphafinch Limited | Information & communication | 2010 |
| Alphie IT Solutions Limited | Information & communication | 2016 |
| Alphirex Studio Ltd | Information & communication | 2025 |
| Alpine Health Limited | Health & social care | 2015 |
| Alpine Smart Healthcare Ltd | Health & social care | 2020 |
| Alpine Tire Recycling Ltd | Water & waste | 2025 |
| Alpinecrest Consulting Ltd | Professional & scientific | 2026 |
| Alpom Consultancy Ltd | Health & social care | 2020 |
| Alps Agility Limited | Information & communication | 2020 |
| Alps Home Improvements Ltd | Construction | 2018 |
| Alps Properties Ltd | Real estate | 2019 |
| ALR Advanced Lifting & Rigging Group Ltd | Construction | 2023 |
| ALR Aesthetic Consulting Ltd | Professional & scientific | 2024 |
| ALR Training & Event Medical Services Ltd | Education | 2016 |
| Alrauf Engineering Ltd | Professional & scientific | 2025 |
| Alreet Limited | Administrative & support | 2010 |
| ALS Roofing (Milton Keynes) Ltd. | Construction | 2019 |
| ALS Roofing Ltd | Construction | 2026 |
| ALS Trans Ltd | Transport & logistics | 2019 |
| Alsil & Sons Limited | Wholesale & retail | 2023 |
| Alsil Limited | Manufacturing | 2016 |
| ALT Street Lettings Ltd | Real estate | 2024 |
| Altadecca Pearl UK Ltd | Wholesale & retail | 2021 |