| Aquatem Services Limited | Administrative & support | 2023 |
| Arak Business Limited | Wholesale & retail | 2025 |
| Arbel Holdings Limited | | 2023 |
| ARC Building Services Limited | Construction | 2015 |
| ARC Mortgage Solutions Ltd | Financial services | 2018 |
| ARC Solutions Scotland Limited | Information & communication | 2017 |
| Arcana 7 Ltd | Other services | 2019 |
| Archibald Mcaulay & SON Limited | Construction | 1987 |
| Argyle Cars Limited | Transport & logistics | 2003 |
| ARH Contractors Ltd | Construction | 2016 |
| Arhamali Limited | Hospitality | 2026 |
| Aribow Developments Ltd | Real estate | 2025 |
| ARK Adventures Limited | Real estate | 2026 |
| Armila Sustainability Services Ltd | Real estate | 2019 |
| Aromeh Limited | Real estate | 2018 |
| Arrybarry Ltd | Wholesale & retail | 2017 |
| Artisan Hardwood Flooring Ltd | Wholesale & retail | 2011 |
| Arty Solutions Limited | Wholesale & retail | 2020 |
| Arvesa Consultancy Ltd | Professional & scientific | 2017 |
| Arzoo Collection Ltd | Wholesale & retail | 2026 |
| AS Logistic Solutions Ltd | Transport & logistics | 2023 |
| AS Print Engineering Limited | Manufacturing | 2023 |
| Asar Investments Limited | Real estate | 2016 |
| Asbestos Building Surveys Limited | Other services | 1999 |
| ASC Installations Ltd | Construction | 2025 |
| Ascendia Trading Ltd | Wholesale & retail | 2024 |
| Ascendtech Services Ltd | Administrative & support | 2024 |
| ASN Energy Consultants Ltd | Information & communication | 2024 |
| ASP Properties Leicester Ltd | Real estate | 2016 |
| Aspect Lighting Design.Co.Uk Ltd | Professional & scientific | 2011 |
| Aspirare Search and Selection Limited | Administrative & support | 2024 |
| Aspire Investments (Leicester) Limited | Real estate | 2021 |
| Asplin Interior Design Ltd | Construction | 2019 |
| Asset Compliance Group Ltd | Construction | 2026 |
| Assure Asbestos Ltd | Construction | 2022 |
| Assure Project Management Ltd | Construction | 2026 |
| Astoria Advisory Group Ltd | Information & communication | 2025 |
| Astra Alarms Limited | Manufacturing | 1990 |
| Astra Piping Limited | Construction | 2012 |
| Astraview Double Glazing Limited | Construction | 2013 |
| At&Co Ltd | Wholesale & retail | 2025 |
| AT8T Ltd | Real estate | 2018 |
| ATF Learning Limited | Administrative & support | 2017 |
| Athene Co-Invest RE Affiliate 1A Ltd. | | 2019 |
| Athene Co-Invest RE Affiliate 2A Ltd. | | 2022 |
| Athene Co-Invest RE Affiliate Holding 2 Ltd. | | 2022 |
| Athene Co-Invest RE Affiliate Holding Ltd. | | 2021 |
| Athene Life RE Ltd. | | 2019 |
| Athletic Academics Limited | Real estate | 2015 |
| Atlantic View Care Home Limited | Health & social care | 2020 |
| Atlas Global Property Ltd | Real estate | 2025 |
| Ature Service Limited | Professional & scientific | 2023 |
| AU Automation Limited | Other services | 2000 |
| Auchnasavil Battery Storage Limited | Professional & scientific | 2021 |
| Audra J Macphee Ltd | Other services | 2024 |
| Audrey Campbell Hair Ltd | Other services | 2023 |
| Auld Apple Tree Limited | Agriculture & fishing | 2024 |
| Aurora Ceiling Designs Ltd | Construction | 2021 |
| Austin LEE Developments Limited | Construction | 2021 |
| Autint Ltd | Wholesale & retail | 2008 |
| Auto Kampus Limited | Wholesale & retail | 2023 |
| Auto Safety Centre (Hamilton) Limited | Wholesale & retail | 2002 |
| Auto Services (Hamilton) Limited | Wholesale & retail | 2018 |
| Auto-Motivated Solutions Limited | Wholesale & retail | 2017 |
| Autoboss Ltd | Wholesale & retail | 2025 |
| Autocris Limited | Transport & logistics | 2019 |
| Autonomous Speed Ltd | Transport & logistics | 2025 |
| Autozone Holdings Ltd | Wholesale & retail | 2024 |
| AV Food Ltd | Wholesale & retail | 2018 |
| Avak Properties Ltd | Real estate | 2021 |
| Avant Group Scotland Ltd | Construction | 2020 |
| Average Speed Ltd | Wholesale & retail | 2017 |
| Avocet Enterprises Ltd | Wholesale & retail | 2011 |
| Avon Developments Ltd. | Real estate | 2005 |
| Avonbridge Builders Limited | Construction | 1998 |
| Avondale Music School Limited | Education | 2025 |
| Avondale Plumbing Ltd | Construction | 2012 |
| Avongreen Abodes Limited | Construction | 2014 |
| Avor Contracts (Joinery) Ltd | Construction | 2024 |
| Avor Contracts Ltd | Professional & scientific | 2017 |
| Axis Storage Solutions Limited | Manufacturing | 1992 |
| Axis Transport Services Limited | Transport & logistics | 2002 |
| AXR Consulting Ltd | Health & social care | 2019 |
| Ayaz Style Ltd | Other services | 2016 |
| AYL Associates Ltd | Agriculture & fishing | 2015 |
| Ayla Medics Ltd | Health & social care | 2023 |
| AYR Windscreens Limited | Wholesale & retail | 2015 |
| Ayrshire Care Homes Limited | Professional & scientific | 2021 |
| Ayrshire Windscreens Limited | Manufacturing | 2011 |
| Azhan Enterprises Ltd | Transport & logistics | 2025 |
| Azimuth Management Limited | | 2011 |
| Azmaher Limited | Wholesale & retail | 2025 |
| Azmat Holding PAK Limited | Real estate | 2026 |
| B & D Acquisitions Ltd | Construction | 2019 |
| B J M Design Limited | Manufacturing | 2017 |
| B S R Car Sales Ltd | Wholesale & retail | 2018 |
| B&A Services (Derby) Limited | Real estate | 2020 |
| B&C Electrics Ltd | Construction | 2022 |
| B.B.S (SCO) Ltd | Other services | 2016 |
| B.M.A Roofing & Cladding Ltd | Construction | 2016 |