| ARK CAP Ltd | Real estate | 2023 |
| ARK Commercial Finance Ltd | Financial services | 2022 |
| ARK Concepts Ltd | Professional & scientific | 2013 |
| Arkke Hub Ltd | Professional & scientific | 2024 |
| Arlet Homes Limited | Construction | 2003 |
| Armeda Ltd | Wholesale & retail | 2015 |
| Armour Developments Ltd | Real estate | 2017 |
| Armstrong and North Ltd | Wholesale & retail | 2018 |
| Armstrong Pipework Services Limited | Construction | 2010 |
| Army of FEW Ltd | Professional & scientific | 2016 |
| Armzn Ltd | Wholesale & retail | 2023 |
| Arnold Heal Limited | Wholesale & retail | 1955 |
| Aroc Waste Management Ltd | Water & waste | 2022 |
| Around the Island Properties Limited | Construction | 2016 |
| Arra Premier Limited | Real estate | 2026 |
| Arraghey Ltd | Professional & scientific | 2016 |
| Arreton Valley Engineering Limited | Manufacturing | 2021 |
| Arreton Valley Tractors Limited | Professional & scientific | 1977 |
| Arrow Commercial Catering Services Limited | Manufacturing | 2002 |
| Art IT Services Ltd | Information & communication | 2026 |
| Art Parcel Limited | Manufacturing | 2016 |
| Artenson Property Ltd | Real estate | 2025 |
| Artheo Properties Ltd | Real estate | 2024 |
| Arthur Brothers Group Limited | Financial services | 2018 |
| Arthur Brothers Haulage Limited | Transport & logistics | 2018 |
| Arthur Stone Holdings Company Ltd | Financial services | 2024 |
| Arthur Stone Investment Strategies Ltd | Construction | 2024 |
| Arthur Stone Wealth Management Ltd | Professional & scientific | 2025 |
| Artworx Gallery Ltd | Wholesale & retail | 2016 |
| Arundell Promotions Ltd | Arts & recreation | 2022 |
| AS Car Repairs Centre Ltd | Wholesale & retail | 2026 |
| AS Khera Limited | Transport & logistics | 2024 |
| AS123 Investment Company Limited | Financial services | 2026 |
| Asbestos Consultancy (SW) Ltd | Construction | 2024 |
| Ascendancy Group Limited | Financial services | 2018 |
| Ascendancy Internet Marketing Limited | Professional & scientific | 2006 |
| Ascent Development Limited | Construction | 2015 |
| Ascent Wealth Management Ltd | Financial services | 2019 |
| Asdajo Ltd | Wholesale & retail | 2024 |
| Asdigital Ltd | Information & communication | 2016 |
| ASF Estates Ltd | Construction | 2018 |
| ASF Lettings Ltd | Real estate | 2022 |
| Asgard Innovations Ltd | Professional & scientific | 2020 |
| ASH Haulage Ltd | Transport & logistics | 2022 |
| ASH Lane Management Company (I.W) Limited | Households | 2021 |
| Ash's Convenience Store Ltd | Wholesale & retail | 2017 |
| ASH, Health and Safety Consultancy Ltd | Professional & scientific | 2020 |
| Asha Property Ltd | Real estate | 2021 |
| Ashanti Ltd | Wholesale & retail | 2023 |
| Ashborne Court (Sandown) Management Company Limited | Households | 1989 |
| Ashburn Layne Properties Ltd | Real estate | 2025 |
| Ashburton Assets Ltd | Real estate | 2026 |
| Ashcare Limited | Health & social care | 2022 |
| Ashcombe Court Management Company Limited | Real estate | 2000 |
| Ashleen & Soniya Ltd | Wholesale & retail | 2025 |
| Ashteck Group Ltd | Information & communication | 2019 |
| Ashteck Media Limited | Information & communication | 2015 |
| Ashton Property Group Limited | Real estate | 2020 |
| Asia Benz Limited | Real estate | 2005 |
| Asia Flavours Ltd | Hospitality | 2020 |
| Asia Halal Foodstore Ltd | Wholesale & retail | 2018 |
| Asian Taste NPT Ltd | Hospitality | 2023 |
| ASK Auto Recycling Ltd | Wholesale & retail | 2022 |
| Asli's Beauty Room Ltd | Other services | 2025 |
| Aslw Consultants Limited | Professional & scientific | 2017 |
| ASM Admin Services Ltd | Administrative & support | 2025 |
| Asociacion Latinoamericana DE Mujeres EN LA Oncologia CYF | Education | 2022 |
| Asociatia Romanilor DIN Marea Britanie CIC | Hospitality | 2023 |
| ASP Properties & Management Ltd | Real estate | 2019 |
| Aspen Financial (Cowes) Limited | Financial services | 2017 |
| Aspire Consultancy & Services Ltd | Information & communication | 2022 |
| Aspire Trading Ltd | Wholesale & retail | 2018 |
| Aspirenet Limited | Information & communication | 2011 |
| Asprou Barbers Ltd | Other services | 2018 |
| Assembl Limited | Manufacturing | 2024 |
| Asset Decarbonisation Services Ltd | Professional & scientific | 2022 |
| Assets Jewellery Limited | Wholesale & retail | 1996 |
| Association of Chartered Physiotherapists in Neurology | Information & communication | 2017 |
| Astadost and Company UK Limited | Wholesale & retail | 2021 |
| Astadost Properties Ltd | Real estate | 2024 |
| Astec Coatings Europe Ltd | Construction | 2006 |
| Aston Foods Limited | Hospitality | 2021 |
| Astons MAN With a Van Ltd | Transport & logistics | 2025 |
| Astral Plumbing Limited | Construction | 2010 |
| Astro Squirrel Ltd | Information & communication | 2022 |
| Astrum Elementone Limited | Professional & scientific | 2008 |
| Astrum-Ip Limited | Professional & scientific | 2004 |
| ASW Property Rentals Limited | Real estate | 2025 |
| Asweeney Consulting Ltd | Professional & scientific | 2021 |
| AT Bristol Ltd | Other services | 2024 |
| AT Geotechnical Consultants Ltd | Professional & scientific | 2023 |
| AT Installations Limited | Construction | 2013 |
| AT8 Promotions Ltd | Arts & recreation | 2022 |
| Ataf Salim Business Services Limited | Professional & scientific | 2016 |
| Atbwrs Ltd | Other services | 2025 |
| ATH Corporate Ltd | Other services | 2025 |
| Athenae LC Limited | Administrative & support | 2025 |
| Athene Group Ltd | Professional & scientific | 2026 |
| Atherley Court Residents Company Limited | Households | 2001 |
| ATI2UDE Care Limited | Health & social care | 2025 |