| Ardview Holdings Ltd | Construction | 2022 |
| Arete PM Consulting Ltd | Professional & scientific | 2021 |
| Arete PM Healthcare Ltd | Health & social care | 2024 |
| ARG Instruments Limited | Professional & scientific | 2022 |
| Argesului Ltd | Transport & logistics | 2025 |
| Aria Food Limited | Manufacturing | 2016 |
| Aria Inspection Ltd | Professional & scientific | 2019 |
| Aria Restaurant Ltd | Hospitality | 2025 |
| Ariariana Ltd | Construction | 2023 |
| Arizon Trading Ltd | Wholesale & retail | 2026 |
| ARK Building Enhancements Ltd | Construction | 2019 |
| ARK Kashmir Ltd | Wholesale & retail | 2024 |
| ARK Vehicle Centre Ltd | Wholesale & retail | 2025 |
| ARL Jefferson Property Limited | Real estate | 2022 |
| Armstrong Foulkes LLP | | 2013 |
| Armstrong Joinery N.E. Limited | Construction | 2024 |
| ARO Carcare Ltd | Manufacturing | 2018 |
| Arora Partnership Limited | Hospitality | 2026 |
| Array Energy Ltd | Professional & scientific | 2025 |
| Array Test and Termination Limited | Construction | 2024 |
| Arroyo Pueblo Ltd | Professional & scientific | 2015 |
| Arshman Logistics Ltd | Transport & logistics | 2025 |
| Artav Holdings Limited | Financial services | 2021 |
| Artav Limited | Arts & recreation | 2012 |
| Artemis NE Ltd | Financial services | 2025 |
| Arthur’S World Ltd | Real estate | 2021 |
| Arvis Consultancy Limited | Wholesale & retail | 2026 |
| Arwsafety Ltd | Professional & scientific | 2025 |
| ARY Group Ltd | Wholesale & retail | 2020 |
| Aryan Barber's Ltd | Other services | 2024 |
| AS (Northeast) Limited | Information & communication | 2024 |
| AS 1 Mobile Limited | Wholesale & retail | 2015 |
| AS Mechanical Solutions Ltd | Wholesale & retail | 2019 |
| Asadenj Ltd | Transport & logistics | 2025 |
| Asante Intl Limited | Other services | 2011 |
| Ascension Rope Access Ltd | Construction | 2022 |
| Ascot & Smith Property Ltd | Real estate | 2015 |
| ASG Engineering Services Limited | Professional & scientific | 2022 |
| ASH & Co PVT Ltd | Other services | 2021 |
| ASH Creative Digital Ltd | Administrative & support | 2023 |
| Ashall Hospitality (SSA) LLP | | 2023 |
| Ashbridge Limited | Information & communication | 2020 |
| Ashbrookes Design & Build Limited | Construction | 2019 |
| Ashbrookes Developments Ltd | Construction | 2024 |
| Ashbrookes Group Limited | Construction | 2022 |
| Ashbrookes Inspired Limited | Construction | 2022 |
| Ashbrookes Renovate Ltd | Construction | 2019 |
| Ashburner (NE) Limited | Professional & scientific | 2010 |
| Ashe Accommodation Ltd | Real estate | 2025 |
| Ashe Electrical Limited | Construction | 2011 |
| Ashley Burgess Limited | Health & social care | 2024 |
| Ashmark Services Limited | Professional & scientific | 2007 |
| Ashrep Ltd | Professional & scientific | 2025 |
| Ashvale Cleaning Services Ltd | Administrative & support | 2026 |
| Asif Taxis Limited | Transport & logistics | 2025 |
| ASK Project Consultants Limited | Construction | 2023 |
| Askews Limited | Extraterritorial | 2005 |
| Askews Solicitors Limited | Professional & scientific | 2005 |
| ASM Technical Limited | Construction | 2015 |
| ASM1.HEALTHCARE Limited | Professional & scientific | 2015 |
| Asmara Healthcare Ltd | Health & social care | 2023 |
| Asnod Ltd | Administrative & support | 2021 |
| Asoah Ltd | Wholesale & retail | 2025 |
| Aspen Flats 1-3 Ltd | Households | 2015 |
| Aspire 25 Limited | Real estate | 2024 |
| Aspire Beauty (NE) Limited | Other services | 2016 |
| Aspire Fmcg Ltd | Administrative & support | 2021 |
| Aspire Home Interiors Limited | Wholesale & retail | 2021 |
| Aspire Learning Partnership - a Co-Operative Trust | Education | 2014 |
| Assan Ltd | Wholesale & retail | 2025 |
| Assemblelux Limited | Manufacturing | 2011 |
| Assessable Technology Limited | Information & communication | 2024 |
| Associated Guest Houses Limited | Hospitality | 2006 |
| Associated Risks Northern Limited | Administrative & support | 2011 |
| Astare Trading Ltd | Wholesale & retail | 2025 |
| Astbury Park Properties Ltd | Real estate | 2024 |
| Astra Circuit Tech Ltd | Manufacturing | 2025 |
| Astro Marketing Limited | Information & communication | 2026 |
| Astrocart Ltd | Information & communication | 2022 |
| Astrocart UK Ltd | Information & communication | 2020 |
| Astrologic Ltd | Information & communication | 2026 |
| Astrun Ltd | Wholesale & retail | 2026 |
| Astute Commercial Brokers Limited | Financial services | 2025 |
| Astute Financial & Mortgage Advisers Ltd | Financial services | 2018 |
| ASV Braintree Limited | Hospitality | 2021 |
| Ater Solutions Limited | Transport & logistics | 2026 |
| Atha and Co Solicitors Limited | Professional & scientific | 1993 |
| Atha Construction Limited | Construction | 2020 |
| Atha Developments (NO. 1) Limited | Other services | 2013 |
| Atha Developments (NO. 2) Limited | Other services | 2017 |
| Atha Developments (NO. 3) Limited | Other services | 2018 |
| Atha Developments (NO. 4) Limited | Other services | 2024 |
| Atha Group Holdings Limited | Financial services | 2023 |
| Atharva Consulting Limited | Wholesale & retail | 2025 |
| Athos Art Ltd | Arts & recreation | 2022 |
| Atkinson Northern Limited | Professional & scientific | 1980 |
| Atkinson Plant Services Ltd | Manufacturing | 2025 |
| Atlantic Events NE Ltd | Arts & recreation | 2017 |
| Atlas Consultant Engineers Ltd | Professional & scientific | 2024 |
| Atlas Industrial Management Limited | Construction | 2019 |