| Also UK Holdings Limited | Financial services | 2025 |
| ALT Associates Ltd | Professional & scientific | 2024 |
| ALT Business Tech Ltd | Professional & scientific | 2017 |
| ALT Literary Press Ltd | Information & communication | 2026 |
| ALT ST Property Group Ltd | Real estate | 2017 |
| ALT ST Room Solutions Limited | Real estate | 2019 |
| ALT Street Commercial Limited | Real estate | 2023 |
| Altaera Creative Ltd | Information & communication | 2025 |
| Altanova Group Ltd | Wholesale & retail | 2021 |
| Altavista Europe Limited | Wholesale & retail | 2015 |
| Altazimuth Limited | Professional & scientific | 2010 |
| ALTEA13 Ltd | Hospitality | 2022 |
| Alter-House Ltd | Construction | 2016 |
| Altered Self Limited | Information & communication | 2012 |
| Alternate Digital Ltd | Information & communication | 2026 |
| Alternative Networks Limited | Extraterritorial | 1998 |
| Alternative the Food Group Ltd | Hospitality | 2024 |
| Altigma Ltd | Wholesale & retail | 2026 |
| Altitude Advantage Ltd | Education | 2024 |
| Altitude Software Limited | Information & communication | 1999 |
| Altixo Limited | Wholesale & retail | 2025 |
| Alto Consultancy Ltd | Administrative & support | 2024 |
| Alto Diem Limited | Information & communication | 2023 |
| Altoba Investments Ltd | Real estate | 2021 |
| Alton Cars and Vans Ltd | Wholesale & retail | 2005 |
| Altovale Limited | Construction | 1989 |
| Alumco Ltd | Manufacturing | 2025 |
| Aluminium Design Solutions Ltd | Manufacturing | 2014 |
| Aluvier Limited | Administrative & support | 2023 |
| Aluxe Rooms Ltd | Real estate | 2025 |
| Alva Advisory Partners Ltd | Professional & scientific | 2026 |
| Alviero Trading Ltd | Wholesale & retail | 2026 |
| Always Pass Limited | Education | 2021 |
| Always Smart Service Limited | Real estate | 2023 |
| Alwayson Group Limited | Professional & scientific | 2002 |
| Alwayson Limited | Information & communication | 2000 |
| Alwon Properties Ltd | Real estate | 2022 |
| Alybobo Ltd | Wholesale & retail | 2026 |
| Alyn Logistics Ltd | Transport & logistics | 2019 |
| AM & NK Properties Ltd | Real estate | 2022 |
| AM Brothers Construction Ltd | Construction | 2022 |
| AM Dynamics Ltd | Information & communication | 2025 |
| AM Goods and Transport Ltd | Wholesale & retail | 2023 |
| AM Premier Investments Ltd | Real estate | 2025 |
| AM Recruit Ltd | Administrative & support | 2023 |
| AM Recycle Ltd | Wholesale & retail | 2021 |
| AM2 Planning Ltd | Professional & scientific | 2023 |
| AM2PM Property Solutions Ltd | Real estate | 2020 |
| AM2PM Tyres Ltd | Wholesale & retail | 2024 |
| Amabhizinisi Limited | Hospitality | 2025 |
| Amacam Ltd | Extraterritorial | 2014 |
| Amaco Holdings Limited | Real estate | 2023 |
| Amag Express Ltd | Transport & logistics | 2024 |
| Amagi Media Private Ltd | Information & communication | 2018 |
| Amagi Media UK Private Limited | Information & communication | 2023 |
| Amaib's Store Ltd | Wholesale & retail | 2023 |
| Amalfi Properties Limited | Real estate | 2021 |
| Amambay Limited | Wholesale & retail | 2023 |
| Aman Plumbing & Heating Supplier Limited | Wholesale & retail | 2024 |
| Amana Group Ltd | Wholesale & retail | 2025 |
| Amanah Tech Ltd | Wholesale & retail | 2025 |
| Amanseq Ltd | Information & communication | 2024 |
| Amar Motors UK Ltd | Wholesale & retail | 2020 |
| Amar Retail Ltd | Wholesale & retail | 2020 |
| Amar UK Group Ltd | Wholesale & retail | 2020 |
| Amar Vehicle Management Limited | Administrative & support | 2024 |
| Amara Beauty Academy Ltd | Other services | 2025 |
| Amara Consulting Limited | Information & communication | 2019 |
| Amaru R. Limited | Information & communication | 2020 |
| Amaxs Construction Ltd | Construction | 2016 |
| Amaxs Design Limited | Construction | 2020 |
| Amayya Limited | Hospitality | 2022 |
| Amaz Value Ltd | Wholesale & retail | 2022 |
| Amazing Grace Resources & Fashions Ltd | Wholesale & retail | 2023 |
| Amazing Grace Superstore Ltd | Wholesale & retail | 2019 |
| Amazing Investments UK Limited | Real estate | 2019 |
| Amazing Living UK Limited | Real estate | 2018 |
| Amazing Steps Ventures Ltd | Information & communication | 2011 |
| Amazonia Sky Limited | Other services | 2016 |
| Amba Company Secretarial Services Limited | Professional & scientific | 2006 |
| Amba Logistics Ltd | Transport & logistics | 2013 |
| Amba Secretaries Limited | Professional & scientific | 2006 |
| Ambassador Cleaning Contracts Limited | Administrative & support | 2003 |
| Ambassador F.C. Plumbing Ltd | Construction | 2017 |
| Ambassador Holdings Ltd. | Financial services | 1986 |
| Amber Asthetics Services Ltd | Other services | 2024 |
| Amber Client Limited | Administrative & support | 2017 |
| Amber EAT Limited | Hospitality | 2017 |
| Amber EYE Ltd | Arts & recreation | 2017 |
| Amber Jane Limited | Extraterritorial | 2008 |
| Amber Tabby Limited | Agriculture & fishing | 2022 |
| Amber-May Limited | Information & communication | 2025 |
| Amberleigh Gardens (Sarratt) Management Company Limited | Households | 2005 |
| Amberleigh Homes Limited | Construction | 1999 |
| Amberwood Property Ltd | Real estate | 2026 |
| Ambition Acquisition Limited | Professional & scientific | 2023 |
| Ambos Properties Ltd | Real estate | 2024 |
| Ambrella Healthcare Service Ltd | Health & social care | 2026 |
| Ambrose International Ltd | Administrative & support | 2009 |
| Ambrose Lynch Limited | Education | 2018 |