| Adfinity Media Ltd | Professional & scientific | 2023 |
| ADP Online Ltd | Information & communication | 2019 |
| Adriano Sabia Limited | Health & social care | 2021 |
| Advance BPO Connects Ltd | Administrative & support | 2025 |
| Advancechoice Property Management Limited | Real estate | 1992 |
| Advanced Air Conditioning & Refrigeration Limited | Manufacturing | 2000 |
| Advanced GUM Therapy and Referral Centre Ltd | Health & social care | 2024 |
| Adviserplus Business Solutions Limited | Information & communication | 2001 |
| Adviserplus Holdings Limited | Financial services | 2014 |
| Aeaid Limited | Health & social care | 2025 |
| Aedaley Ltd | Professional & scientific | 2023 |
| Aegis FD Ltd | Professional & scientific | 2026 |
| Aerial Sports Ltd | Arts & recreation | 2020 |
| Aeroplane Collection Limited(The) | Arts & recreation | 1973 |
| AES MED Limited | Health & social care | 2020 |
| Aesthetics by Cath Ltd | Health & social care | 2025 |
| AF Warwick Limited | Arts & recreation | 2022 |
| Afep Dental Ltd | Health & social care | 2024 |
| AFS Media Limited | Information & communication | 2022 |
| Aga's 2 Boilers Ltd | Construction | 2025 |
| AGK Medical Ltd | Health & social care | 2026 |
| Agm&M Limited | Other services | 2023 |
| Agmdent Limited | Health & social care | 2024 |
| Agusdon Limited | Health & social care | 2016 |
| Agusdon Properties Limited | Real estate | 2021 |
| Ahmed Elleithy GP Ltd | Health & social care | 2024 |
| Ahmed Elleithy Holdings Ltd | Financial services | 2026 |
| Ahmed Elleithy Stocks and Shares Ltd | Financial services | 2026 |
| Ahml Services Ltd | Health & social care | 2025 |
| Ahrsa Limited | Wholesale & retail | 2025 |
| AI for Business Ltd | Information & communication | 2024 |
| AI for Business Partnerships Ltd | Information & communication | 2024 |
| AIC Forster Properties Limited | Real estate | 2019 |
| AIM55 Limited | Professional & scientific | 2024 |
| Aimi Health Ltd | Health & social care | 2022 |
| Ainsty Dental Practice Limited | Health & social care | 2013 |
| Aintree Coaches (International) Limited | Transport & logistics | 1997 |
| Airflow Climate Control Ltd. | Construction | 1999 |
| Airflow Group Ltd. | Construction | 1997 |
| Airflow Office Solutions Ltd. | Construction | 1999 |
| Airflow Storage Solutions Ltd. | Construction | 1999 |
| Aitoolshed Ltd | Information & communication | 2023 |
| AJ Radley Ltd | Construction | 2026 |
| AJ Realty Group Ltd | Real estate | 2022 |
| AJ Seymour Ltd | Health & social care | 2024 |
| AJM Dentistry Limited | Health & social care | 2021 |
| AJT Global Limited | Hospitality | 2025 |
| AJT Implants Limited | Health & social care | 2014 |
| Ajtdental Ltd | Health & social care | 2024 |
| AJW Medical Ltd | Health & social care | 2025 |
| AKI Capital Ltd | Financial services | 2026 |
| Alan Design Concept Limited | Construction | 2015 |
| ALB Medical Ltd | Health & social care | 2022 |
| Albayan Online Ltd | Education | 2020 |
| Alchem (Merseyside) Limited | Water & waste | 1984 |
| Alco Manufacturing Limited | Manufacturing | 2003 |
| Alexander Beard Employee Ownership Trust Limited | Financial services | 2025 |
| Alexander Beard International Benefits (UK) Ltd. | Financial services | 2018 |
| Alexander Beard Investment Management Limited | Financial services | 2001 |
| Alexander Beard Ltd. | Financial services | 2003 |
| Alexander Ford Furnishings Limited | Manufacturing | 2020 |
| Alextrician Limited | Construction | 2026 |
| Alfie's Wine Bars Limited | Hospitality | 2016 |
| Aliaj Properties Ltd | Real estate | 2025 |
| Alison Crellin Limited | Health & social care | 2012 |
| Alkmak Ltd | Real estate | 2023 |
| Allegiant (NW) Limited | Construction | 2024 |
| Allegiant Paints Limited | Wholesale & retail | 2025 |
| Allpyne Ltd | Information & communication | 2019 |
| Allpyne Property Ltd | Real estate | 2025 |
| ALS Pallets Limited | Manufacturing | 2025 |
| Alternative Approach Family Support Ltd | Health & social care | 2024 |
| Alternative Approach Supported Accommodation Ltd | Hospitality | 2017 |
| Alternative Property Solutions Ltd | Households | 2020 |
| Altrain ADR Limited | Administrative & support | 2015 |
| AM Midlands Builders Ltd | Construction | 2024 |
| AM Recruitment MCR Ltd | Administrative & support | 2024 |
| Amanath Limited | Real estate | 2019 |
| AMC Healthcare Solutions Ltd | Health & social care | 2023 |
| Amcg Ltd | Health & social care | 2021 |
| AMI Metals UK Limited | Manufacturing | 2012 |
| Amica Homecare Limited | Health & social care | 2019 |
| Amjcoatings Ltd | Manufacturing | 2019 |
| AMP Transport Safe and Secure Ltd | Transport & logistics | 2023 |
| Amrock Onsite Mechanical Services Ltd | Manufacturing | 2012 |
| Amsoft Systems Limited | Information & communication | 2001 |
| Amy-Nicole Hair Designer Ltd | Other services | 2023 |
| AN Health Ltd | Health & social care | 2023 |
| Anchor & Hope IT Solutions Ltd | Extraterritorial | 2019 |
| Anchorpath CIC | Health & social care | 2025 |
| Anderson Independent Funeral Directors Limited | Other services | 2012 |
| Andreasazas Ltd | Health & social care | 2025 |
| Andrew Horne Ltd | Health & social care | 2009 |
| Andrew Jones Dental Practice Limited | Health & social care | 2008 |
| Andrew M Lyons Ltd | Health & social care | 2022 |
| Andrew Medical Ltd | Health & social care | 2026 |
| Anevro Ltd | Health & social care | 2025 |
| Angel Analysis Ltd | Professional & scientific | 2019 |
| Anger Issues Rage Rooms Ltd | Arts & recreation | 2024 |
| Anglezarke Clinical Services Ltd | Administrative & support | 2019 |