| Aspen Willow Ltd | Wholesale & retail | 2025 |
| Aspro Maintenance Limited | Construction | 2006 |
| Assiduously Limited | Professional & scientific | 2022 |
| Assistiv CIC | Information & communication | 2018 |
| ASSURE24 Limited | Information & communication | 2010 |
| Asta Labista Ltd | Wholesale & retail | 2025 |
| Asteroid Labs Limited | Wholesale & retail | 2026 |
| Asyst 365 Limited | Information & communication | 2013 |
| AT Architectural Services Ltd | Professional & scientific | 2024 |
| ATD Resin Floors Limited | Professional & scientific | 2020 |
| Atelier LUX Ltd | Wholesale & retail | 2026 |
| Atheli-Care Ltd | Other services | 2026 |
| Atkins K Limited | Wholesale & retail | 2015 |
| Atkinson Waine Ltd | Wholesale & retail | 2025 |
| Atlantic Breeze Foods Ltd | Hospitality | 2017 |
| Atlanticis Consulting Ltd | Information & communication | 2025 |
| Atlas Company Properties Ltd | Real estate | 2024 |
| Atpu Ltd | Administrative & support | 2018 |
| ATROOFING27 Ltd | Construction | 2023 |
| ATS Holdings Limited | Wholesale & retail | 2020 |
| ATS Pro Equipment Limited | Wholesale & retail | 2020 |
| Atsf Ltd | Real estate | 2017 |
| Attaboy Media Ltd. | Information & communication | 2007 |
| Attaboy Television Ltd. | Information & communication | 2003 |
| Attract Exhibitions Ltd | Administrative & support | 2014 |
| Auburndale Process Consultancy Limited | Professional & scientific | 1997 |
| Aulia Limited | Real estate | 2013 |
| Aulona Limited | Transport & logistics | 2020 |
| Aureus Enterprise Ltd | Wholesale & retail | 2020 |
| Aurics Consultancy Limited | Professional & scientific | 2014 |
| Aurics One Limited | Professional & scientific | 2019 |
| Aurion Estates Ltd | Real estate | 2025 |
| Aust Holdings Limited | Professional & scientific | 2025 |
| Auto Cleanse Limited | Real estate | 1984 |
| Auto Cool Services (UK) Ltd | Energy | 2013 |
| Auto HQ (HX) Limited | Wholesale & retail | 2024 |
| Auto Key Security Ltd | Wholesale & retail | 2026 |
| Auto Movements Limited | Wholesale & retail | 2024 |
| Auto Vehicle Logistics Ltd | Wholesale & retail | 2017 |
| Auto Waze Limited | Wholesale & retail | 2024 |
| Autobahn Ltd | Wholesale & retail | 2014 |
| Autobody Refinishing Ltd | Wholesale & retail | 2021 |
| Autocare (Halifax) Limited | Wholesale & retail | 1991 |
| Autofix Halifax Ltd | Wholesale & retail | 2016 |
| Automica Limited | Information & communication | 2010 |
| Automotive Paint Supplies Limited | Wholesale & retail | 2006 |
| Automotive Solutions (Yorkshire) Ltd | Wholesale & retail | 2021 |
| Automotive Volkswagen Breakers Limited | Wholesale & retail | 2019 |
| Autorize Ltd | Wholesale & retail | 2024 |
| AVA Group Holdings Limited | Professional & scientific | 2018 |
| AVA Properties Ltd | Real estate | 2018 |
| AVA Recycling Ltd | Water & waste | 2018 |
| Available Domain Ltd | Information & communication | 2022 |
| Avant Consult Ltd | Professional & scientific | 2003 |
| Avelune Wellness Ltd | Wholesale & retail | 2026 |
| Avena Developments Ltd | Construction | 2025 |
| Avena Estates Ltd | Real estate | 2025 |
| Avena Group Ltd | Financial services | 2025 |
| Aventa Technologies Ltd | Information & communication | 2026 |
| Aventhera Therapeutics Private Limited | Professional & scientific | 2025 |
| Aveyard Limited | Construction | 2024 |
| Aviz Properties Ltd | Real estate | 2026 |
| Avva Developments Limited | Construction | 2013 |
| Avysproperties Ltd | Real estate | 2025 |
| AW Trading Ltd | Households | 2025 |
| AWA Essentials Limited | Wholesale & retail | 2024 |
| AWD Services Limited | Professional & scientific | 2020 |
| AWG Joinery Ltd | Construction | 2023 |
| AWS Dynamics Ltd | Hospitality | 2025 |
| Axia Data Management Limited | Information & communication | 1997 |
| Axminster Court Limited | Construction | 2023 |
| Axminster CT Mgmt Company Ltd | Households | 2024 |
| AYA Digital Marketing Ltd | Professional & scientific | 2024 |
| AYA Holdings SPV Limited | Financial services | 2024 |
| Ayappa PVT Ltd | Hospitality | 2025 |
| Ayaz Couriers Ltd | Transport & logistics | 2025 |
| Aycliffe Asset Management Limited | Financial services | 2025 |
| Ayrton Property Ltd | Real estate | 2019 |
| Ayrton Trading Limited | Professional & scientific | 2016 |
| Ayubowan Street Food (Halifax) Limited | Hospitality | 2025 |
| Ayup Digital Limited | Information & communication | 2014 |
| AZ Therapy Services Ltd | Health & social care | 2023 |
| Azad Construction Limited | Construction | 2023 |
| Azam & Associates Healthcare Ltd | Health & social care | 2010 |
| Azamjaan Healthcare Limited | Health & social care | 2025 |
| Azamjaan Property Ltd | Real estate | 2021 |
| Azden Limited | Health & social care | 2009 |
| Azeal Ltd | Wholesale & retail | 2022 |
| Aziz Properties HX Ltd | Real estate | 2026 |
| AZL Construction Limited | Construction | 2023 |
| Azure Holdings Limited | Financial services | 2015 |
| Azureationnova Ltd | Wholesale & retail | 2025 |
| B & a Bespoke Upholstery Limited | Other services | 2023 |
| B & M Holmes (Properties) Limited | Real estate | 1995 |
| B a Vintage Clothing Ltd | Wholesale & retail | 2018 |
| B Ainley Commercials Limited | Wholesale & retail | 2004 |
| B Armitage Plastics Limited | Construction | 2013 |
| B B Excavations Limited | Construction | 2023 |
| B Consultancy Services Ltd | Professional & scientific | 2026 |
| B Findlay Ltd | Professional & scientific | 2021 |