| Askcosta Limited | Construction | 2020 |
| Askedfor Art Limited | Arts & recreation | 2017 |
| Askg Properties Limited | Real estate | 2026 |
| ASL Transport Ltd | Other services | 2016 |
| Aslam Property Group Ltd | Real estate | 2025 |
| ASM Trading & Consulting Ltd | Wholesale & retail | 2020 |
| ASN Sports Capital Ltd | Education | 2026 |
| Aspect Assembly Limited | Manufacturing | 1993 |
| Aspect Ecology Limited | Professional & scientific | 2005 |
| Aspect in View Limited | Professional & scientific | 2021 |
| Aspenbrook Limited | Administrative & support | 1984 |
| Aspirational Investments Limited | Other services | 2018 |
| Aspire Business Systems Consultancy Ltd | Professional & scientific | 2026 |
| Aspire Surveyors Cheshire Ltd | Professional & scientific | 2018 |
| Aspire Wealth Investment Ltd | Real estate | 2025 |
| Aspiring Analytics Ltd | Professional & scientific | 2022 |
| Asporter Limited | Construction | 2005 |
| Aspyr Consulting Ltd | Professional & scientific | 2023 |
| Asqs Projects Limited | Professional & scientific | 2012 |
| Asquare Supplies Ltd | Wholesale & retail | 2023 |
| ASR Accessories Ltd | Wholesale & retail | 2021 |
| ASR International Limited | Administrative & support | 2023 |
| Asra Freelancer Ltd | Wholesale & retail | 2026 |
| Assembly Property Holdings Limited | Financial services | 2014 |
| Assess the Risk Limited | Other services | 2014 |
| Assessment Associates Limited | Education | 2017 |
| Asset Associates Limited | Administrative & support | 2016 |
| Asset Media Ltd | Professional & scientific | 2023 |
| Asset Technology Limited | Information & communication | 2015 |
| Asset UK Services Limited | Other services | 2021 |
| ASSETS55 Ltd | Professional & scientific | 2007 |
| Assist and Care Limited | Health & social care | 2010 |
| Assist Heat Limited | Construction | 2018 |
| Assist Pharmacist Locums Limited | Health & social care | 2022 |
| Associated Consulting Engineers International Limited | Professional & scientific | 1998 |
| Associated Engineering Materials Ltd | Administrative & support | 2003 |
| Association of Company Registration Agents Limited(The) | Other services | 1975 |
| Association of Vehicle Adaptation Manufacturers Limited | Other services | 2021 |
| Assure Security Services Ltd | Administrative & support | 2015 |
| Assure Start Consultancy Ltd | Information & communication | 2021 |
| Assured Assessments Ltd | Health & social care | 2024 |
| Assured Care (Stockport) Ltd. | Health & social care | 2010 |
| Assured FM Limited | Administrative & support | 2009 |
| Assured Roofing Ltd | Construction | 2024 |
| Assured Vending Group Ltd | Other services | 2025 |
| Assurepoint Advisory Ltd | Information & communication | 2026 |
| Astbury Investments Limited | Real estate | 2020 |
| Asteras Transport Services Limited | Transport & logistics | 2007 |
| Asterismos Ltd | Wholesale & retail | 2017 |
| Astir Properties Limited | Real estate | 2011 |
| Astley Moss Limited | Construction | 2015 |
| Astof Limited | Health & social care | 2023 |
| Aston Services Limited | Administrative & support | 2023 |
| Aston Smith Ltd | Information & communication | 2013 |
| Astra HR Limited | Administrative & support | 2025 |
| Astrinas - Asian Trade and Investment Limited | Professional & scientific | 2013 |
| Astro Antenna Limited | Manufacturing | 2014 |
| Astro Blue Investments Ltd | Real estate | 2023 |
| Astute Estates Ltd | Real estate | 2009 |
| Asymptotic Limited | Information & communication | 2019 |
| Asyndesis Ltd | Health & social care | 2026 |
| Asys Properties Ltd | Real estate | 2024 |
| AT Health Ltd | Wholesale & retail | 2022 |
| AT Health Properties Ltd | Real estate | 2024 |
| AT Home With the Bardsleys Ltd | Wholesale & retail | 2017 |
| AT Long Last Ltd | Wholesale & retail | 2022 |
| AT Padel Ltd | Arts & recreation | 2025 |
| AT Reef Ltd | Financial services | 2025 |
| AT Thirty Three Limited | Wholesale & retail | 2015 |
| ATA Nail Supply Limited | Wholesale & retail | 2025 |
| ATB Distribution Ltd | Wholesale & retail | 2025 |
| ATC Health & Safety Solutions Ltd | Professional & scientific | 2010 |
| Ateam Wardobes Ltd | Construction | 2026 |
| Atelier Casa Limited | Real estate | 2023 |
| Atelier N Ltd | Professional & scientific | 2024 |
| Atelier Two Limited | Professional & scientific | 2018 |
| Ateno Systems Ltd | Information & communication | 2022 |
| Atex Limited | Wholesale & retail | 2000 |
| Atfm Ltd | Administrative & support | 2024 |
| Atgani Property Ltd | Construction | 2025 |
| Athena 61 Limited | Administrative & support | 2018 |
| Athena Professional Technical Services Limited | Construction | 2011 |
| Athenaaerialartsacademy Limited | Arts & recreation | 2023 |
| Athenian Building Services Ltd | Construction | 2024 |
| Atherton Electrical Limited | Construction | 2012 |
| Athletic Minds Limited | Construction | 2024 |
| Athlon X Beast Limited | Wholesale & retail | 2018 |
| ATK04 Limited | Wholesale & retail | 2025 |
| Atkins Court Property Management Ltd | Real estate | 2018 |
| Atkinson Baker Associates Ltd | Administrative & support | 2025 |
| Atkinson Ventures Ltd | Wholesale & retail | 2024 |
| Atlantic Estates Holding Ltd | Construction | 2024 |
| Atlantic International Limited | Extraterritorial | 2008 |
| Atlantic Renewables Ltd | Construction | 2011 |
| Atlantic Ringmer 1 Ltd | Construction | 2019 |
| Atlantick Limited | Administrative & support | 2010 |
| Atlantis Building Surveyors Ltd | Professional & scientific | 2026 |
| Atlas Aesthetics Limited | Wholesale & retail | 2022 |
| Atlas Assets Group Limited | Administrative & support | 2025 |
| Atlas Autos North West Ltd | Wholesale & retail | 2026 |