| Algack for Trade Ltd | Construction | 2024 |
| Algorithm Accountancy Services Limited | Professional & scientific | 2015 |
| ALH Marketing Limited | Professional & scientific | 2025 |
| ALI Cook Ltd | Information & communication | 2017 |
| Alison Straw Consulting Ltd | Administrative & support | 2008 |
| Alistair Todd Ltd | Information & communication | 2008 |
| Alive and Kicking Publishing Limited | Information & communication | 2011 |
| Aliya Naushad Traders Ltd | Wholesale & retail | 2022 |
| ALK Solutions Limited | Information & communication | 2021 |
| Alker Holdings Limited | Financial services | 2018 |
| Alkhawlani Ltd | Wholesale & retail | 2024 |
| ALL About Obesity C.I.C. | Health & social care | 2021 |
| ALL About Sports Events Ltd | Professional & scientific | 2020 |
| ALL Brands Distribution Limited | Wholesale & retail | 2019 |
| ALL Darts Limited | Wholesale & retail | 2026 |
| ALL Nation Super Store Ltd | Wholesale & retail | 2023 |
| ALL Secure Alarms Ltd | Administrative & support | 2025 |
| ALL Shots Towards the Hole Ltd | Professional & scientific | 2022 |
| ALL Surveys Great and Small Limited | Professional & scientific | 2020 |
| ALL Things Home Cleaning Ltd | Administrative & support | 2023 |
| Allagi Agency Ltd | Real estate | 2017 |
| Allan Smyth Audio Visual Ltd. | Administrative & support | 2014 |
| Allegro Silanus Ltd | Hospitality | 2024 |
| Alligator Hardscape and Plant Ltd | Agriculture & fishing | 2019 |
| Allithorn Limited | Real estate | 2021 |
| Allsky Optics Ltd | Manufacturing | 2018 |
| Allstars Media Limited | Extraterritorial | 2026 |
| Allus Projects Limited | Information & communication | 2025 |
| Almeida Enterprises Limited | Information & communication | 2017 |
| Almisbah Group Ltd | Wholesale & retail | 2024 |
| Almsford Court Maintenance Limited | Households | 1989 |
| ALP Admin UK Ltd | Administrative & support | 2019 |
| ALP Property Investing Ltd | Real estate | 2023 |
| ALP Sourcing Ltd | Administrative & support | 2023 |
| Alpha Solutions York Limited | Professional & scientific | 2024 |
| Alpha Training & Consultants Ltd | Construction | 2011 |
| Alpha Transfers Harrogate Ltd | Transport & logistics | 2025 |
| Alpine Technologies Holdings Ltd | Financial services | 2026 |
| Alpineflor Limited | Construction | 2014 |
| Alrawaj Almutatawwira Ltd | Wholesale & retail | 2026 |
| ALS Global Real Estate Limited | Real estate | 2025 |
| Alshalal Global Ltd | Water & waste | 2020 |
| Alsop Wealth Management Limited | Financial services | 2019 |
| Alsuqour Ltd | Hospitality | 2022 |
| Alsuwaije Company Ltd | Wholesale & retail | 2024 |
| Altage Ltd | Energy | 2022 |
| Altair Advisory LLP | | 2022 |
| Altajer Ltd | Wholesale & retail | 2022 |
| Altamira Management Limited | Real estate | 2008 |
| Altanex Events Ltd | Administrative & support | 2025 |
| Alternis Mediation Limited | Professional & scientific | 2023 |
| Altha UK Ltd | Construction | 2023 |
| Althulooj Almutanathirah Training for Wholesale and Retail Trade Company Ltd | Wholesale & retail | 2025 |
| Altitude Consulting Limited | Information & communication | 2011 |
| Alton Saint-Clair Limited | Extraterritorial | 2025 |
| Altura Consulting Services Limited | Professional & scientific | 2026 |
| Aluminium Europe Ltd | Wholesale & retail | 2026 |
| Alveary Grange Limited | Real estate | 2019 |
| Alveary Limited | Real estate | 2019 |
| Alvic Construction (Northern) Limited | Construction | 1965 |
| Alvic Holdings Limited | Construction | 2023 |
| Alvico Limited | Real estate | 2025 |
| Alyssia Fleur Marylebone School of Dance Ltd | Education | 2024 |
| Alyssia Fleur School of Dance Ltd | Education | 2020 |
| AM Business and Accountancy Services Ltd | Professional & scientific | 2015 |
| AM Gillett Limited | Health & social care | 2018 |
| AM4ZON Ltd | Extraterritorial | 2019 |
| AMA Construction and Trading Ltd | Wholesale & retail | 2022 |
| Amado Developments Ltd | Construction | 2024 |
| Amado Holdings Ltd | Real estate | 2024 |
| Amado Homes Ltd | Real estate | 2018 |
| Amado Properties Limited | Real estate | 2017 |
| AMALF1 Limited | Wholesale & retail | 2021 |
| Amalthea Holdings Limited | Professional & scientific | 2011 |
| Amara Jane UK Limited | Manufacturing | 2017 |
| Amasa Limited Ltd | Wholesale & retail | 2023 |
| Amber Fluid Ltd | Extraterritorial | 2012 |
| Amberstone Scaffolding Ltd | Administrative & support | 2025 |
| Amberwolf Limited | Information & communication | 2021 |
| Ambler Properties Ltd | Real estate | 2025 |
| Ambridge Group Limited | Extraterritorial | 2026 |
| AMC Windows & Doors Ltd | Construction | 2016 |
| Amco Developments Group Limited | Real estate | 2011 |
| AMD Property Consulting Limited | Real estate | 2019 |
| AMEL1A Limited | Extraterritorial | 2020 |
| Amelia India PR Ltd | Administrative & support | 2025 |
| Amenbury Investments Limited | Real estate | 2023 |
| Amer for Trading Ltd | Professional & scientific | 2022 |
| American Luggage Ltd | Wholesale & retail | 2026 |
| Amethyst Prime Ltd | Wholesale & retail | 2023 |
| AMF 1AD Limited | Arts & recreation | 2011 |
| AMG Architectural Limited | Professional & scientific | 2017 |
| Amgs Electrical Limited | Administrative & support | 2006 |
| Amgwells Limited | Professional & scientific | 2023 |
| Amicis Data Limited | Professional & scientific | 2018 |
| Amicon (Europe) Limited | Real estate | 1998 |
| Amicus Estate Solutions Limited | Professional & scientific | 2020 |
| Amlskincare Limited | Health & social care | 2018 |
| Ammar Build Ltd | Construction | 2021 |
| AMP Digital Ltd | Information & communication | 2013 |