| Allen Real Estate Limited | Real estate | 2025 |
| Allextra Limited | Administrative & support | 2023 |
| Alleyway Homes Ltd | Real estate | 2024 |
| Allgas Heating Services Ltd | Construction | 2006 |
| Allgreen Properties Limited | Real estate | 2023 |
| Alliance Business Exchange Ltd | Administrative & support | 2021 |
| Alliance Deco Limited | Manufacturing | 2021 |
| Alliance Facilities Limited | Construction | 2000 |
| Alliance Office Space Ltd | Administrative & support | 2024 |
| Allianz Innovation Trade UK Ltd | Wholesale & retail | 2020 |
| Allianz Inspections Limited | Construction | 2025 |
| Allied Property Investment Limited | Real estate | 2025 |
| Allo Vera Catering Service Ltd | Hospitality | 2023 |
| Allout Games Limited | Arts & recreation | 2019 |
| Alloxx Ltd | Construction | 2025 |
| Alloy FIX Ltd | Wholesale & retail | 2019 |
| Allstar Hydraulics Ltd | Manufacturing | 2019 |
| Alluppy Limited | Wholesale & retail | 2022 |
| Allura Solutions Limited | Information & communication | 2011 |
| Allure Clinic & Training Academy Ltd | Other services | 2025 |
| Allvora Company Ltd | Wholesale & retail | 2025 |
| ALM Build Ltd | Construction | 2022 |
| ALM Football Consultancy Ltd | Professional & scientific | 2019 |
| ALM Immigration Services Ltd | Professional & scientific | 2024 |
| Alma Mater Tuition Ltd | Education | 2023 |
| Alma Mater Tutoring Limited | Education | 2024 |
| Almustaqbal Language Centre Limited | Other services | 2023 |
| ALN Unic Design Ltd | Construction | 2024 |
| Alnader Solutions Limited | Construction | 2023 |
| Alog Homes Limited | Real estate | 2019 |
| Alondon Constructions Ltd | Construction | 2025 |
| Alone Services Limited | Transport & logistics | 2022 |
| Alorn Limited | Wholesale & retail | 2024 |
| Alpas Group Ltd | Administrative & support | 2018 |
| Alpas Housing Ltd | Real estate | 2017 |
| Alpas Transport Ltd | Administrative & support | 2018 |
| Alpha Corporate Services Limited | Administrative & support | 2025 |
| Alpha Crew Services Limited | Construction | 2023 |
| Alpha Disability Employment Training & Advocacy (Adeta) Community Interest Company | Administrative & support | 2018 |
| Alpha International Ministries Limited | Other services | 2017 |
| Alpha Kappa Sigma Limited | Administrative & support | 2018 |
| Alpha Professional Contractors Limited | Construction | 2019 |
| Alpha Property Management Services Limited | Real estate | 2007 |
| Alpha Scan Ltd | Health & social care | 2014 |
| Alpha Smart Ltd | Administrative & support | 2016 |
| Alpha Specialists Limited | Professional & scientific | 2006 |
| Alpha Threads Ltd | Wholesale & retail | 2025 |
| Alpha Unify Business Solutions Limited | Administrative & support | 2015 |
| Alpha Vital Ltd | Health & social care | 2021 |
| Alpha Youth UK | Health & social care | 2010 |
| Alpha-Lite Services Ltd | Administrative & support | 2008 |
| Alphano Business Ltd | Wholesale & retail | 2017 |
| Alphavest Limited | Financial services | 2023 |
| Alpi Acct Limited | Professional & scientific | 2018 |
| Alplex Ltd | Wholesale & retail | 2023 |
| Alpo Investment Ltd | Financial services | 2024 |
| Alsted Ltd | Construction | 2015 |
| ALT Shift Ltd | Information & communication | 2020 |
| Altb Consulting Ltd | Professional & scientific | 2024 |
| Alteo Builders Ltd | Construction | 2023 |
| Alternative Bedrooms Limited | Construction | 2007 |
| Alternative Cleaning Solutions & Support Services Ltd | Other services | 2022 |
| Alternative Property Services Limited | Real estate | 2002 |
| Altimate Care Services UK Ltd | Administrative & support | 2019 |
| Altin Transport Ltd | Transport & logistics | 2019 |
| Altir Limited | Construction | 2025 |
| ALU Windows & Doors Ltd | Construction | 2013 |
| Alubarikaloju International Travels Ltd | Administrative & support | 2020 |
| Alucorp Ltd | Wholesale & retail | 2025 |
| Aluroar Ltd | Construction | 2023 |
| ALV Transport Limited | Transport & logistics | 2020 |
| Alva Shoes Limited | Administrative & support | 2010 |
| Alvala Construction Ltd | Construction | 2022 |
| Alvero Group Ltd. | Administrative & support | 2025 |
| Alverstones Limited | Real estate | 2005 |
| Alvin Tech Solution Ltd | Information & communication | 2025 |
| Alx-Auto Ltd | Other services | 2019 |
| Alyan Traders Ltd | Wholesale & retail | 2017 |
| Alyana Motors Ltd | Wholesale & retail | 2026 |
| Alyssa Healthcare Ltd | Health & social care | 2026 |
| AM and NS Ltd | Real estate | 2025 |
| AM Arising Community Interest Company | Information & communication | 2019 |
| AM Construction and Roofing Ltd | Construction | 2021 |
| AM Electrical Solutions London Ltd | Construction | 2026 |
| AM Finance Accounting Limited | Professional & scientific | 2023 |
| AM Lettings and Investments Ltd | Real estate | 2020 |
| AM Plumbing Heating Direct Limited | Construction | 2015 |
| AM UK Law Ltd | Professional & scientific | 2011 |
| Am's Kitchen Ltd | Hospitality | 2025 |
| AM2 Romford Ltd | Education | 2022 |
| AMA Alliance Ltd | Wholesale & retail | 2024 |
| Amaa Solutions Ltd | Health & social care | 2016 |
| Amadeus Management Ltd | Professional & scientific | 2024 |
| Amal International Limited | Wholesale & retail | 2021 |
| Aman Kitchen & Bedroom Ltd | Manufacturing | 2025 |
| Aman Properties Limited | Real estate | 2010 |
| Amanah Holds Ltd | Households | 2026 |
| Amanah Property Management Ltd | Households | 2026 |
| Amanah Solutions Ltd | Professional & scientific | 2026 |
| Amanda Levack Consulting Limited | Professional & scientific | 2026 |