| Apollo Decorating Services Ltd | Construction | 2025 |
| Apollo Endosurgery UK Ltd | Wholesale & retail | 2014 |
| Apolodor Construction Services Ltd | Construction | 2021 |
| Apolodor Estates Limited | Real estate | 2025 |
| Apolodor Ltd | Construction | 2008 |
| Appii PTY Ltd | Administrative & support | 2016 |
| Applebough Recruitment Ltd | Administrative & support | 2021 |
| Applegarth Manor (Oulton) Management Company Limited | Households | 2015 |
| Appleton Downs Management Company Limited | Households | 2010 |
| Appleton Property Holdings Ltd | Households | 2022 |
| Applied Healthcare Products Limited | Wholesale & retail | 2020 |
| Appstech Ltd | Information & communication | 2022 |
| Apsley & Waterend Tyres Limited | Wholesale & retail | 2017 |
| Apsley Barbers Ltd | Other services | 2023 |
| Apsley Fish Bar Ltd | Hospitality | 2022 |
| Apsley Mills (Blocks a B and D) Flat Management Company Limited | Households | 2001 |
| Apsley Mills (Blocks E F and G) Flat Management Company Limited | Households | 2001 |
| Apsley Quay Management Company Limited | Households | 2019 |
| Apsley Smile Limited | Health & social care | 2017 |
| Apsley Technologies Limited | Information & communication | 2018 |
| Apsleyhill Ltd | Transport & logistics | 2022 |
| Apt-Skidata Limited | Manufacturing | 1998 |
| Aqua Residents Limited | Households | 2016 |
| Aquacision Limited | Administrative & support | 2008 |
| Aquadan Ltd | Construction | 2025 |
| Aquatics Management Ltd | Education | 2021 |
| AR Auto Group Ltd | Wholesale & retail | 2023 |
| AR Crafts Ltd | Wholesale & retail | 2021 |
| AR LEATHER49 Ltd | Wholesale & retail | 2020 |
| AR Property & Investments Ltd | Real estate | 2019 |
| Araadigit Ltd | Information & communication | 2008 |
| Arabica Espresso Services Limited | Manufacturing | 2010 |
| Arabica House Limited | Real estate | 1998 |
| Aramena Ltd | Construction | 2016 |
| Aratek Ltd | Information & communication | 2025 |
| ARB Worx Engineering Ltd | Manufacturing | 2023 |
| Arbor Construction Ltd | Construction | 2021 |
| Arbor Lane Winnersh Berkshire Limited | Households | 2015 |
| ARC Bedford Limited | Wholesale & retail | 2018 |
| ARC Daventry Limited | Wholesale & retail | 2016 |
| ARC Engineering Solutions Ltd | Manufacturing | 2026 |
| ARC Locksmithing Ltd | Administrative & support | 2025 |
| Arca Project Ltd | Professional & scientific | 2018 |
| Arcade Services Limited | Transport & logistics | 2024 |
| Arcade Walk Vaping Ltd | Wholesale & retail | 2018 |
| Archer Bidco Limited | Financial services | 2019 |
| Archer Care Recruitment Ltd | Administrative & support | 2023 |
| Archer Midco Limited | Financial services | 2019 |
| Archibald IT Consulting Ltd | Information & communication | 2015 |
| Archideo Ltd | Professional & scientific | 2025 |
| Architetris Ltd | Information & communication | 2026 |
| Archsign Ltd | Professional & scientific | 2019 |
| Archway Court RTM Company Limited | Households | 2020 |
| Archwell Consultancy Limited | Professional & scientific | 2022 |
| Arcom Design Ltd | Other services | 2011 |
| Ardayus Homes Ltd | Real estate | 2018 |
| Arden Fields Management Company Limited | Households | 2014 |
| Area Relocation Ltd | Hospitality | 2025 |
| Arena Tiles and Bathrooms Ltd | Construction | 2024 |
| ARG Integrated Design Ltd | Professional & scientific | 2021 |
| Argon NPS (Holdings) Limited | Information & communication | 2014 |
| Argon NPS Limited | Information & communication | 2014 |
| Argon Property Holdings Limited | Real estate | 2017 |
| Aria Residential Care Ltd | Health & social care | 2022 |
| Arif's Cafe Hemel Ltd | Hospitality | 2025 |
| ARK Dynamics Ltd | Professional & scientific | 2025 |
| ARK INV Group Ltd | Households | 2025 |
| ARK Newco Limited | Financial services | 2025 |
| Arkley Labels LLP | | 2016 |
| ARL Design and Construction Ltd | Construction | 2024 |
| Arloesi Group Ltd | Professional & scientific | 2026 |
| Arloesi Hub Ltd | Administrative & support | 2026 |
| Arloesi Ltd | Professional & scientific | 2024 |
| Arman & Co Accountancy Limited | Professional & scientific | 2019 |
| Armistead Cleaning Services Limited | Administrative & support | 2012 |
| Armitage Supplies Ltd | Wholesale & retail | 2026 |
| Armstrong Landscapes Limited | Administrative & support | 2001 |
| Armycom Ltd | Construction | 2017 |
| Arnold Moon Limited | Administrative & support | 1995 |
| Arnold's Attic Limited | Arts & recreation | 2017 |
| Arostransport Limited | Transport & logistics | 2015 |
| Arowfam Ltd | Real estate | 2024 |
| Arqtech Search Ltd | Professional & scientific | 2024 |
| Arsen Architecture Ltd | Professional & scientific | 2016 |
| Art by Toor Ltd | Arts & recreation | 2024 |
| Art Football Limited | Arts & recreation | 2019 |
| Art of Cleaning UK Elite Ltd | Administrative & support | 2025 |
| Artemis Bidco Limited | Financial services | 2021 |
| Artha Global | Education | 2020 |
| Article Consulting Limited | Professional & scientific | 2014 |
| Artigos Ltd | Wholesale & retail | 2020 |
| Artigos Services Ltd | Transport & logistics | 2025 |
| Artisphere Ltd | Real estate | 2026 |
| Artmoon Limited | Transport & logistics | 2023 |
| Artstone 21 Ltd | Manufacturing | 2021 |
| Artworks (Hitchin) Resident Management Company Limited | Households | 2016 |
| Arvin Properties Ltd | Real estate | 2021 |
| Arvin Stores Ltd | Wholesale & retail | 2012 |
| Arya Consultancy Ltd | Information & communication | 2014 |
| Arya Music Ltd | Education | 2020 |