| Apic 1 Ltd | Real estate | 2024 |
| APJ Accountants Limited | Financial services | 2022 |
| Apna Sky Limited | Construction | 2019 |
| Apostolic Bethel Church Ltd | Information & communication | 2026 |
| Appgo Ltd | Information & communication | 2016 |
| Apple Educational Limited | Wholesale & retail | 2004 |
| Apple Seven Limited | Real estate | 2017 |
| Apple Three Limited | Construction | 2006 |
| Appleacre Properties Limited | Real estate | 2001 |
| Applestar Limited | Real estate | 2004 |
| Applieniix Ltd | Wholesale & retail | 2026 |
| Apprintable Limited | Manufacturing | 2015 |
| Appsha Ltd | Wholesale & retail | 2025 |
| Apptributor Limited | Information & communication | 2024 |
| Appyfinance Group Ltd | Information & communication | 2020 |
| Aprove Science | Professional & scientific | 2022 |
| APS Services Ltd | Other services | 2020 |
| Apsidal Holdings Ltd | Financial services | 2023 |
| APT Motor Repairs Ltd | Wholesale & retail | 2023 |
| Aquaberry Ltd | Hospitality | 2016 |
| Aquablu Publishing Ltd | Information & communication | 2022 |
| Aquarius Home Care Limited | Health & social care | 2016 |
| Aquince Accommodation Ltd | Real estate | 2019 |
| Aquince Avante Property Management Ltd | Real estate | 2019 |
| Aquince Construction Services Ltd | Construction | 2016 |
| Aqunex Ltd | Wholesale & retail | 2026 |
| AR Design and Construct Ltd | Construction | 2025 |
| AR SUB Ltd | Hospitality | 2018 |
| ARA Fire Protection Ltd | Construction | 2025 |
| Araav N Ltd | Wholesale & retail | 2022 |
| Arabian American for Integrated Systems Co. Ltd | Administrative & support | 2017 |
| Ararat Building Services Ltd | Construction | 2023 |
| Arav Properties Ltd | Real estate | 2023 |
| ARAY2 Limited | Manufacturing | 2019 |
| ARBE20 Limited | Administrative & support | 2014 |
| Arbee Goods Ltd | Wholesale & retail | 2026 |
| Arcalys Ltd | Professional & scientific | 2025 |
| Arceus Accountancy Ltd | Professional & scientific | 2023 |
| Arch Dental Studio Limited | Health & social care | 2019 |
| Arch Joinery (London) Limited | Real estate | 2010 |
| Arch Joinery Limited | Construction | 2018 |
| Arch Paperlinks Limited | Wholesale & retail | 1996 |
| Archangel Meridian Capital Ltd | Professional & scientific | 2026 |
| Arched Limited | Administrative & support | 2024 |
| Archevolucio Ltd | Professional & scientific | 2010 |
| Archibees Ltd | Professional & scientific | 2022 |
| Archipower Ltd | Professional & scientific | 2024 |
| Archnix Group Ltd | Information & communication | 2025 |
| Arcilia Lawrence Ltd | Health & social care | 2020 |
| Arcondene Limited | | 1978 |
| Arcsine Zero Lifts Ltd | Professional & scientific | 2026 |
| Arct Ocean Limited | Administrative & support | 2021 |
| Areeva Limited | Professional & scientific | 2025 |
| Arena Grill Ltd | Hospitality | 2024 |
| Arena Grill Restaurant Ltd | Hospitality | 2024 |
| ARG Innovation Ltd | Construction | 2025 |
| ARH Capital LLP | | 2019 |
| ARH Consultancy Services Ltd | Professional & scientific | 2015 |
| Arhanse Limited | Real estate | 2015 |
| Aria Exim Ltd | Wholesale & retail | 2025 |
| Aria London Ltd | Manufacturing | 2025 |
| Ariadne Consulting Ltd | Information & communication | 2026 |
| Ariana Electrical Service Limited | Manufacturing | 2020 |
| Ariana Multi Services Ltd | Hospitality | 2016 |
| Arihant London Limited | Real estate | 2018 |
| Arihantsofton Ltd | Information & communication | 2023 |
| Ariminumtruffles Ltd | Wholesale & retail | 2024 |
| Arinton UK Limited | Information & communication | 2010 |
| Arioni. Ltd | Administrative & support | 2019 |
| Arionit Ltd | Information & communication | 2025 |
| Aritrad Limited | Financial services | 2025 |
| Arjai Investments Limited | Real estate | 2022 |
| Arjannati Limited | Real estate | 2020 |
| Arjun (UK) Ltd | Professional & scientific | 2012 |
| Arjun MOT and Repairs Ltd | Wholesale & retail | 2024 |
| ARK Online Limited | Wholesale & retail | 2019 |
| ARK Systems London Limited | Administrative & support | 2010 |
| Arka Beauty Supply Ltd | Wholesale & retail | 2025 |
| Arka Developments Ltd | Construction | 2025 |
| Arkala Ltd | Health & social care | 2021 |
| Arkatalent Tech Limited | Information & communication | 2024 |
| Arkavio Ltd | Information & communication | 2026 |
| Arkn Limited | Financial services | 2007 |
| Arko UK Limited | Real estate | 2008 |
| Arkworks Builders Limited | Construction | 2009 |
| ARM AV Ltd | Professional & scientific | 2023 |
| Armaan Investments Limited | Real estate | 2026 |
| Arman Central Heating Limited | Construction | 2021 |
| Armn Limited | Administrative & support | 2025 |
| Armollinen Ltd | Wholesale & retail | 2022 |
| Armont Ltd | Professional & scientific | 2023 |
| Arnett International Ltd | Administrative & support | 2024 |
| Arnett UK Ltd | Transport & logistics | 2021 |
| Arojas Property Services Ltd | Households | 2025 |
| Aroma Caribe Limited | Wholesale & retail | 2019 |
| Aron Projects Limited | Wholesale & retail | 2019 |
| Aronn Limited | Wholesale & retail | 2024 |
| Arooj Khalid Ltd | Wholesale & retail | 2025 |
| Arora Alliance Ltd | Financial services | 2025 |
| Aroy Limited | Health & social care | 2015 |