| Allen Property Maintenance Limited | Construction | 2026 |
| Allerford Management Company Limited | Households | 2007 |
| Allerton C&S GL Limited | Health & social care | 2016 |
| Allerton C&S N Limited | Health & social care | 2016 |
| Allerton C&S NE Limited | Health & social care | 2011 |
| Allerton C&S SC Limited | Health & social care | 2004 |
| Allerton C&S SE Limited | Health & social care | 2011 |
| Allerton C&S SW Limited | Health & social care | 2009 |
| Allerton Developments Ltd | Construction | 2018 |
| Allerton Group Limited | Professional & scientific | 2018 |
| Allerton SPV18 Limited | Real estate | 2020 |
| Allerton SPV24 Limited | Real estate | 2019 |
| Alley Consultancy Ltd | Manufacturing | 2026 |
| Alley Strength and Nutrition Ltd | Education | 2023 |
| Alliance for African Minds Ltd | Professional & scientific | 2024 |
| Alliance Park Ltd | Information & communication | 2017 |
| Alliance Services Ltd | Professional & scientific | 2008 |
| Allied Identity (UK) T/A Swiss One OIL and GAS Limited | Wholesale & retail | 2024 |
| Allied Taxis Watford Ltd | Transport & logistics | 2008 |
| Allies Project Management Limited | Construction | 2019 |
| Allies Property Holdings Limited | Construction | 2019 |
| Allmed Ltd | Wholesale & retail | 2019 |
| Allsfar International Limited | Financial services | 2025 |
| Allstar Logistics Limited | Other services | 2017 |
| Allsure Property Solutions Limited | Construction | 2020 |
| Allum Lane Property Management Limited | Real estate | 1988 |
| Allwyn Entertainment Ltd | Financial services | 2021 |
| ALM Finance Consulting Limited | Professional & scientific | 2025 |
| Alma Pearl Limited | Wholesale & retail | 2022 |
| Almari Developments Ltd | Real estate | 2017 |
| Almeida & Zuliani Motorcycles Ltd | Wholesale & retail | 2015 |
| Almond Close Residents Company Limited | Households | 2019 |
| Almond Investments CDM Limited | Financial services | 2003 |
| Almondyard Ltd | Wholesale & retail | 2019 |
| Almurtajiz Ltd | Wholesale & retail | 2024 |
| Alna Property Ltd | Real estate | 2024 |
| Aloriamo Limited | Arts & recreation | 2026 |
| Alpa Estates Limited | Real estate | 2018 |
| Alpha Executive Jobs Limited | Administrative & support | 2001 |
| Alpha Exterior Ltd | Administrative & support | 2026 |
| Alpha Online Sales Limited | Administrative & support | 2002 |
| Alpha Phex Ltd | Real estate | 2023 |
| Alpha Promo Limited | Administrative & support | 2024 |
| Alpha Sigma Bookkeeping Ltd | Professional & scientific | 2015 |
| Alpha Ventilation Services Ltd. | Construction | 2023 |
| Alpha Workforce Ltd | Financial services | 2016 |
| Alphanetech Limited | Information & communication | 2017 |
| Alphie Foods Ltd | Hospitality | 2021 |
| Alpine International Limited | Real estate | 2022 |
| Alpine Roofing Limited | Construction | 1995 |
| Alquest Services Ltd | Health & social care | 2015 |
| Alquimista Limited | Professional & scientific | 2015 |
| ALS Catering & Transport Company Limited | Manufacturing | 2017 |
| ALS Grab Hire Ltd | Water & waste | 2020 |
| Alsai Leisure Limited | Hospitality | 2001 |
| Alsana Trade Ltd | Wholesale & retail | 2023 |
| Alser Limited | Information & communication | 2007 |
| Alsushe Ltd | Information & communication | 2011 |
| Alta UK Group Ltd | Other services | 2015 |
| Alta UK Properties Ltd | Real estate | 2021 |
| Altaf Enterprises Ltd | Wholesale & retail | 2024 |
| Altan Capital Ltd | Real estate | 2020 |
| Alterra Capital Advisors Limited | Professional & scientific | 2004 |
| Altima Plus LLP | | 2025 |
| Altitude Lifestyle Limited | Professional & scientific | 2016 |
| Altman Properties Limited | Real estate | 2015 |
| Altman Property Holdings Limited | Financial services | 2025 |
| Altogether Agile Limited | Information & communication | 2017 |
| Alton Commercial Estates Limited | Real estate | 2020 |
| Aluminium Unit Limited | Real estate | 2023 |
| Alvin & Alma Ltd | Health & social care | 2022 |
| ALW Consulting Services Limited | Information & communication | 2015 |
| Always Evolving Solutions Ltd | Information & communication | 2014 |
| ALY Services Ltd | Transport & logistics | 2019 |
| Alysha Nicole Consulting UK Ltd | Education | 2025 |
| Alzo Ltd | Transport & logistics | 2019 |
| AM & HE Ltd | Other services | 2017 |
| AM & MG Limited | Other services | 2018 |
| AM Advisors Ltd | Real estate | 2026 |
| AM Chimneys Limited | Construction | 2009 |
| AM GAS & Heating Services Ltd | Construction | 2026 |
| AM Heights Limited | Real estate | 2020 |
| AM Opportunities Ltd | Professional & scientific | 2018 |
| AM Pharma Ltd | Health & social care | 2021 |
| AM Services London Ltd | Manufacturing | 2005 |
| AM Stock Properties Limited | Real estate | 2025 |
| Am&He West Ltd | Real estate | 2025 |
| Am&Sy Limited | Information & communication | 2017 |
| AMA Accounting Limited | Professional & scientific | 2012 |
| AMA Property Company Ltd | Real estate | 2020 |
| AMA Synergy Ltd | Professional & scientific | 2024 |
| AMA Tech Limited | Information & communication | 2022 |
| Amaa Education Ltd | Education | 2019 |
| Amadeus Travel Ltd | Wholesale & retail | 2013 |
| Amafhh Events Ltd | Professional & scientific | 2021 |
| Amafhh Traders Ltd | Financial services | 2022 |
| Amagis Capital Limited | Information & communication | 2013 |
| Amaju Ltd | Wholesale & retail | 2019 |
| Amal Ismail Consulting Ltd | Health & social care | 2018 |
| Amal Real Estate Limited | Real estate | 2026 |