| Arcadis Tetra Tech 1 Limited | Professional & scientific | 2026 |
| Arcadis Tetra Tech 2 Limited | Professional & scientific | 2026 |
| Arcan Media Ltd | Information & communication | 2024 |
| Arcana House Ltd | Arts & recreation | 2026 |
| Arcdat Limited | Information & communication | 2026 |
| Arceilings Limited | Construction | 2023 |
| Arch 258 Ltd | Construction | 2021 |
| Arch Community Homes Ltd | Real estate | 2023 |
| Arch Community Services Ltd | Health & social care | 2013 |
| Arch Concept Ltd | Professional & scientific | 2020 |
| Arch Consultants Ltd | Other services | 2018 |
| Arch Estate Agents Limited | Real estate | 2006 |
| Arch Property Solutions Limited | Real estate | 2010 |
| Archbold Carshop Limited | Wholesale & retail | 1959 |
| Archbold Holdings Limited | Real estate | 1937 |
| Archbold Property Management Limited | Real estate | 2015 |
| Arche Solutions Limited | Transport & logistics | 2012 |
| Archean Ltd | Professional & scientific | 2023 |
| Archella Limited | Construction | 2022 |
| Archella Media Ltd | Information & communication | 2025 |
| Archers Sweets & Special Gifts Ltd | Wholesale & retail | 2018 |
| Archetype Ltd | Information & communication | 2020 |
| Archie 668 Limited | Real estate | 2022 |
| Archie Vaughan Property Investments Ltd | Real estate | 2022 |
| Archipelago BPO Limited | Professional & scientific | 2024 |
| Architectural Glass and Aluminium Limited | Manufacturing | 2019 |
| Architectural Systems Limited | Financial services | 2003 |
| Architecture for Better Living Ltd | Professional & scientific | 2024 |
| Archive North Limited | Hospitality | 2023 |
| Archiwall Ltd | Construction | 2020 |
| Archways Estate Ltd | Real estate | 2019 |
| Arcola Limited | Information & communication | 2017 |
| Arcon Construction Limited | Construction | 2011 |
| Arcon Plant Limited | Extraterritorial | 1983 |
| Arctic Associates Limited | Manufacturing | 2003 |
| Arctic BEE Ltd | Information & communication | 2021 |
| Arctic Breeze Ltd | Manufacturing | 2025 |
| Arctic Elixir Ltd | Hospitality | 2024 |
| Arctic Fish Products Limited | Manufacturing | 2005 |
| Arctic Hayes Limited | Wholesale & retail | 1981 |
| Arctos Group Holdings Ltd | Financial services | 2026 |
| Arcturus Services of London Limited | Professional & scientific | 2021 |
| Arcus Consultants (2018) Ltd | Administrative & support | 2018 |
| ARD (a Really Deep) Clean Ltd | Administrative & support | 2025 |
| ARD Uppal Limited | Arts & recreation | 2016 |
| Ardara Property Holdings Limited | Real estate | 2017 |
| Ardas Suites Ltd | Hospitality | 2025 |
| Ardee Holdings Limited | Financial services | 2026 |
| Ardee Limited | Professional & scientific | 2024 |
| Ardengate Capital Limited | Real estate | 2017 |
| Ardenton Care Holdings Limited | Financial services | 2019 |
| Ardenton Care Propco Limited | Extraterritorial | 2020 |
| Ardl Real Estate Ltd | Real estate | 2014 |
| Ardour Outdoors Ltd | Wholesale & retail | 2023 |
| Ardvark Limited | | 1985 |
| ARE YOU Sure? Limited | Arts & recreation | 2024 |
| Area 15 Limited | Real estate | 2003 |
| Area 6 Limited | Real estate | 2019 |
| Area 66 Limited | Arts & recreation | 2019 |
| Area Concepts Limited | Construction | 2014 |
| Area Projects Ltd | Construction | 2019 |
| Areion Consulting Limited | Professional & scientific | 2017 |
| Areion Limited | Wholesale & retail | 2023 |
| Arena Entertainment (UK) Ltd. | Arts & recreation | 2008 |
| Arena Installations Limited | Professional & scientific | 2022 |
| Arena Parking Leeds Limited | Professional & scientific | 2011 |
| Arena Parking Limited | Professional & scientific | 2011 |
| Arena Partners Limited | Professional & scientific | 2012 |
| Arena Partners Property Limited | Real estate | 2020 |
| Arena Property Management Limited | Real estate | 2026 |
| Arena Tiling Coventry Ltd | Construction | 2013 |
| Ares International Limited | Financial services | 2018 |
| Arete Select Holdings Limited | Real estate | 2017 |
| Arette Management Consultants Ltd | Professional & scientific | 2023 |
| Argantis Ltd | Financial services | 2020 |
| Argantis PHG Ltd | Financial services | 2020 |
| Argantos Ltd | Financial services | 2020 |
| Argantos PHG Ltd | Financial services | 2020 |
| Argent Contemporary Jewellery Limited | Wholesale & retail | 2010 |
| Argento Athletica Ltd | Wholesale & retail | 2026 |
| Argentum Exploration Limited | Professional & scientific | 2012 |
| Argie Roofing UK Ltd | Construction | 2024 |
| Argus Information and Advisory Services UK Ltd | Professional & scientific | 2007 |
| Argyle Wedgwood Properties Limited | Real estate | 2021 |
| Arhoptical Ltd | Health & social care | 2024 |
| Arhum Retail Ltd | Wholesale & retail | 2024 |
| Arhvel (UK) I.T. and Research Ltd | Information & communication | 2025 |
| Aria Care Limited | Health & social care | 2015 |
| Aria Catering Events Limited | Hospitality | 2023 |
| Aria Events Ltd | Professional & scientific | 2019 |
| Aria Suite Ltd | Real estate | 2019 |
| Ariana Cleaning Services Leeds Limited | Administrative & support | 2026 |
| Ariana Hair Studio Ltd | Other services | 2025 |
| Ariannorth Ltd | Wholesale & retail | 2021 |
| Arias Properties Limited | Real estate | 2023 |
| Arias Property Holding Ltd | Construction | 2024 |
| Ariastec Ltd | Arts & recreation | 2023 |
| Arielview Limited | Wholesale & retail | 2021 |
| Arif Holdings (Yorkshire) Ltd | Real estate | 2018 |
| Arif Project Management Services Ltd | Professional & scientific | 2018 |