| Adri Medical Services Limited | Health & social care | 2017 |
| Adroit Fmcg Services Ltd | Professional & scientific | 2019 |
| ADS Car Collections Limited | Transport & logistics | 2019 |
| ADS Unicorn Ltd | Professional & scientific | 2023 |
| Advance Dental Clinic Limited | Health & social care | 2009 |
| Advance Occupational Healthcare Ltd | Real estate | 2019 |
| Advance Property Care Limited | Construction | 2014 |
| Advanced Access Repairs Ltd | Manufacturing | 2022 |
| Advanced Acupuncture Ltd | Health & social care | 2025 |
| Adventa Consulting Ltd | Information & communication | 2023 |
| Adventec Limited | Information & communication | 2025 |
| Adventics Homes Limited | Real estate | 2023 |
| Adventics Ltd | Information & communication | 2020 |
| Adventure Furniture Limited | Manufacturing | 2025 |
| Advertwise Ltd | Professional & scientific | 2018 |
| Aecor International Scaffolding Safety Services Ltd | Other services | 2025 |
| Aecor International Training Ltd | Other services | 2024 |
| Aegis Grid Limited | Information & communication | 2026 |
| Aegis Property Consultancy Limited | Professional & scientific | 2009 |
| AEH Advisory Limited | Professional & scientific | 2022 |
| AEM Systems (Yorkshire) Ltd | Information & communication | 2023 |
| Aer-Sat Communications Limited | Information & communication | 2003 |
| Aerica Trans Limited | Transport & logistics | 2020 |
| Aero-Tek (UK) Limited | Construction | 1992 |
| Aesthetics and Wellness Ltd | Health & social care | 2022 |
| Aesthetics by Helen Limited | Other services | 2025 |
| Aesthetics by Rebecca Ltd | Other services | 2022 |
| Aesthetics Fifty Five Ltd | Other services | 2023 |
| Aeterna Enterprises Limited | Other services | 2025 |
| Aeyweb Ltd | Information & communication | 2025 |
| AF Technical Ltd | Arts & recreation | 2024 |
| Affordable Accountancy Solutions Limited | Professional & scientific | 2014 |
| Affordable Autos (UK) Limited | Wholesale & retail | 2007 |
| Affordable Smart Repair Ltd | Wholesale & retail | 2025 |
| AFK Birmingham Ltd | Hospitality | 2020 |
| Afor (UK) Limited | Professional & scientific | 2014 |
| Afor Accountants Limited | Professional & scientific | 2023 |
| Afor Property Limited | Real estate | 2020 |
| Africa Orphanage Foundation (AOF) | Professional & scientific | 2007 |
| Afridi Healthcare Ltd | Real estate | 2015 |
| Afrikana Leicester Ltd | Hospitality | 2019 |
| Afro Leads Limited | Professional & scientific | 2021 |
| After Dark Mansfield Ltd | Hospitality | 2014 |
| Afterdark Wakefield Ltd | Hospitality | 2015 |
| Agaz Wakefield UK Limited | Education | 2024 |
| AGB Electrical Services Limited | Construction | 2017 |
| Agbrigg General Store Ltd | Wholesale & retail | 2020 |
| Agchem Buyers Limited | Manufacturing | 2020 |
| Agfl Ltd | Wholesale & retail | 2022 |
| AGG Care Consultancy Ltd | Professional & scientific | 2026 |
| Agile Automotive Limited | Wholesale & retail | 2017 |
| Agile Cubed Limited | Professional & scientific | 2015 |
| Agile HR Solutions Limited | Agriculture & fishing | 2009 |
| Agility IS Ltd | Information & communication | 2015 |
| AGK Investments Ltd | Hospitality | 2016 |
| Agni Aesthetics Limited | Health & social care | 2024 |
| AGO Developments Ltd | Professional & scientific | 2023 |
| AGR Ventures Limited | Real estate | 2026 |
| Agricultural and Commercial Supplies Limited | Manufacturing | 1994 |
| AGS Plants and Landscapes Limited | Administrative & support | 2023 |
| AH Legal Assist Ltd | Professional & scientific | 2019 |
| Ahcm Ltd | Hospitality | 2017 |
| Ahhd Ltd | Real estate | 2024 |
| Ahiraa UK Limited | Wholesale & retail | 2021 |
| AHK Property Solutions Ltd | Real estate | 2025 |
| Ahkhan Properties Ltd | Real estate | 2019 |
| Ahuru Homes Limited | Real estate | 2019 |
| AI Enablement Labs Ltd | Information & communication | 2026 |
| AI MED Innovations Limited | Health & social care | 2025 |
| AIB Property Developments Limited | Real estate | 2018 |
| AIF Property Ltd | Real estate | 2025 |
| Air Flow Compressor Services Limited | Manufacturing | 2011 |
| Aircooled Carb Services Limited | Wholesale & retail | 2025 |
| Aire & Calder Limited | Construction | 2005 |
| Airea PLC | Professional & scientific | 1953 |
| Airtec Services (Yorkshire) Limited | Construction | 1997 |
| Aiza Ltd | Administrative & support | 2025 |
| AJ Automotive Wakefield Ltd | Wholesale & retail | 2023 |
| AJ Carter Organ Builder Ltd | Manufacturing | 2011 |
| AJ Coaching Services Limited | Education | 2020 |
| AJ Electrical Services Limited | Construction | 2002 |
| AJ Garden and Landscapes Ltd | Administrative & support | 2026 |
| AJ Property Rentals Ltd | Real estate | 2024 |
| AJ Sons Civils Limited | Construction | 2021 |
| Ajay Gupta Limited | Health & social care | 2023 |
| AJC Professional Services Limited | Professional & scientific | 2017 |
| AJD Property Services Ltd | Real estate | 2014 |
| AJD Security Limited | Manufacturing | 2008 |
| Ajebo Entertainment Ltd | Wholesale & retail | 2024 |
| AJF Lettings Ltd | Real estate | 2024 |
| Ajgendle Limited | Financial services | 2015 |
| AJH Pump Supply & Repair Limited | Manufacturing | 2009 |
| AJH Pump Supply and Repair (Holdings) Ltd | Financial services | 2024 |
| Ajiibes International Limited | Construction | 2020 |
| AJM Sales Limited | Wholesale & retail | 2014 |
| Ajob Electrical Ltd | Construction | 2013 |
| AJR Properties Limited | Real estate | 2017 |
| AJW Developments (Yorkshire) Ltd | Construction | 2025 |
| AJW Entertainment Limited | Arts & recreation | 2020 |
| AK Homes Appliance Ltd | Manufacturing | 2026 |