| Archet WM Limited | Professional & scientific | 2026 |
| Archit Commercial Investments Ltd | Real estate | 2020 |
| Archit Consultancy Services Limited | Information & communication | 2020 |
| Archit Holdings Ltd | Financial services | 2015 |
| Archit Residential Investments Ltd | Real estate | 2020 |
| Architecture Moderne Limited | Wholesale & retail | 2020 |
| Architeuthis Limited | Manufacturing | 1984 |
| Arcturus Architects Ltd | Professional & scientific | 2025 |
| Arcubius Services Ltd | Professional & scientific | 2018 |
| Ardfry Consulting Ltd | Professional & scientific | 2024 |
| Arena 1865 Limited | Administrative & support | 2010 |
| Arena Global Management (CM) Ltd | Construction | 2020 |
| Arena Global Management Ltd. | Other services | 2010 |
| Areti Mortgages Limited | Financial services | 2024 |
| Arfi Group Ltd | Wholesale & retail | 2026 |
| Argonautes Limited | Construction | 2018 |
| Argyle Building Surveyors Limited | Professional & scientific | 2025 |
| Arham Wear Ltd | Wholesale & retail | 2024 |
| Ariel (Advanced Research Into European Lexicography) Ukeig | | 1997 |
| Arielle Jewellery Company Limited | Wholesale & retail | 2022 |
| Ario Analytics Ltd | Information & communication | 2022 |
| Arleen Coach Hire and Services Limited | Transport & logistics | 1976 |
| Arlington House Stall Street Management Company Limited | Households | 2022 |
| ARM Consulting PVT Limited | Information & communication | 2023 |
| Arma Food Limited | Hospitality | 2019 |
| Armed Lions Limited | Professional & scientific | 2005 |
| Armfield Angling Premier Ltd | Administrative & support | 2015 |
| Armin Ltd | Professional & scientific | 2025 |
| Armour Haulage Limited | Extraterritorial | 2013 |
| Arne Maynard Garden Design Holdings Limited | Administrative & support | 2018 |
| Arne Maynard Garden Design Limited | Administrative & support | 2007 |
| Arobase Limited | Professional & scientific | 2017 |
| Arosio Coaching Limited | Professional & scientific | 2020 |
| Arquelia Limited | Professional & scientific | 2024 |
| Arrowspeed Ltd | Transport & logistics | 2004 |
| Arrx Ltd | Information & communication | 2025 |
| Art Accountants Limited | Professional & scientific | 2012 |
| Art From Art Schools Limited | Wholesale & retail | 2022 |
| Art Salon Limited | Wholesale & retail | 2015 |
| Artful Inkling Ltd. | Arts & recreation | 2014 |
| Arthaus Coffee Ltd | Hospitality | 2024 |
| Artifice Limited | Information & communication | 2000 |
| Artimus Contracts Ltd | Professional & scientific | 2022 |
| Artisan Cakes of Bristol Ltd | Manufacturing | 2023 |
| Artisans Yard Ltd | Real estate | 2018 |
| Artowar Ltd | Wholesale & retail | 2023 |
| Artwork Creations Limited | Arts & recreation | 2013 |
| Artwork OWL Ltd | Professional & scientific | 2015 |
| Artyourart Limited | Arts & recreation | 2022 |
| Arudiya Limited | Real estate | 2023 |
| AS Prosperity Limited | Real estate | 2019 |
| Asacollective Ltd | Education | 2025 |
| Asante Media Services Limited | Professional & scientific | 2013 |
| ASC Builders Ltd | Construction | 2018 |
| Ascent U.K. Ltd | Arts & recreation | 2018 |
| Asclepius Medical Distribution Ltd | Health & social care | 2025 |
| Ascott Holdings Ltd | Financial services | 2020 |
| Ascott Ventures Limited | Real estate | 2024 |
| Asetz Ltd | Households | 2020 |
| ASH of Style Ltd | Other services | 2017 |
| Ashfell (SW) Limited | Construction | 2022 |
| Ashgrove 26ABC Ltd | Households | 2018 |
| Ashgrove Court RTM Company Limited | Real estate | 2014 |
| Ashlar Holdings 137 Limited | Real estate | 2018 |
| Ashley Property Developments Limited | Construction | 2018 |
| Ashley Property Syndicate Limited | Real estate | 2015 |
| Ashley Sean Solutions Limited | Administrative & support | 2025 |
| Ashman Ltd | Real estate | 2025 |
| Ashmead Business Centre (Management) Limited | Households | 1990 |
| Ashton Building Contractors Limited | Construction | 1989 |
| Ashura Ltd | Professional & scientific | 2005 |
| Ashworthy Limited | Hospitality | 2006 |
| ASK and Embla Architecture Limited | Professional & scientific | 2020 |
| ASO Production Ltd | Arts & recreation | 2023 |
| ASP Cars Ltd | Wholesale & retail | 2026 |
| Aspect Business Consulting Ltd | Professional & scientific | 2008 |
| Aspect Window Styling Limited | Wholesale & retail | 2014 |
| Aspen Branch Limited | Professional & scientific | 2022 |
| Aspire Bath Ltd | Construction | 2024 |
| Aspire Leadership Development Limited | Professional & scientific | 2013 |
| Aspire to Move Limited | Real estate | 2019 |
| Aspirio Ltd | Education | 2025 |
| Asset Operating Solutions Ltd | Professional & scientific | 2011 |
| Assist Passive Fire Protection Ltd | Wholesale & retail | 2018 |
| Astal Ltd | Other services | 2010 |
| Astin Services Limited | Health & social care | 2019 |
| Astralpoint Limited | Financial services | 1981 |
| Astrantia People Consulting Limited | Administrative & support | 2024 |
| Astro Thoughts Ltd | Education | 2026 |
| Astrobabble Productions Ltd | Information & communication | 2022 |
| Astuta Consulting Limited | Professional & scientific | 2013 |
| Asunta Holdings UK Limited | Financial services | 2025 |
| AT One Group Ltd | Professional & scientific | 2022 |
| AT One Renovation Ltd. | Professional & scientific | 2021 |
| ATA International Trade & Consultancy Ltd | Wholesale & retail | 2018 |
| Atelier Bath Ltd | Wholesale & retail | 2025 |
| Atelier Nursery Ltd | Education | 2013 |
| Atelier RAD Limited | Arts & recreation | 2026 |
| Athena Security Ltd | Administrative & support | 2024 |
| Atilla INK Tattoo Limited | Arts & recreation | 2026 |