| Arocom Ltd | Construction | 2025 |
| Aroma Oriental Peterborough Ltd | Hospitality | 2026 |
| Aromat Property Ltd | Real estate | 2019 |
| Aromatic Media Limited | Information & communication | 2016 |
| Aron Food Centre Ltd | Wholesale & retail | 2023 |
| Arora Global Limited | Transport & logistics | 2023 |
| Arora Medics Ltd | Health & social care | 2021 |
| ARP Dental Care Ltd | Health & social care | 2014 |
| ARP Property Enterprises Ltd | Real estate | 2020 |
| Arqum Limited | Wholesale & retail | 2025 |
| Arrabida Biscotti Limited | Wholesale & retail | 2025 |
| Arrow Autotek Ltd | Professional & scientific | 2022 |
| Arsa Properties Ltd | Real estate | 2023 |
| Arsa Trade Ltd | Wholesale & retail | 2025 |
| Arsir Ltd | Transport & logistics | 2023 |
| Arstu Properties Ltd | Real estate | 2014 |
| Art and Craft Sales UK Ltd. | Wholesale & retail | 2015 |
| Art Earth Tech Limited | Education | 2016 |
| Art Haulage Limited | Transport & logistics | 2026 |
| Art in Stone Ltd | Construction | 2023 |
| Art-Pal Limited | Transport & logistics | 2022 |
| Arta Construction Limited | Construction | 2018 |
| Artazak Ltd | Health & social care | 2024 |
| Artco Property Ltd | Real estate | 2025 |
| Artefact Consult Ltd | Extraterritorial | 2020 |
| Artemida Limited | Real estate | 2026 |
| Artfully Media Ltd | Professional & scientific | 2022 |
| Arthur Beeston Law Limited | Information & communication | 2022 |
| Arthur GEE (Holding) Limited | Financial services | 2018 |
| Arthur GEE (Thorney) Limited | Agriculture & fishing | 1948 |
| Arthur Stanley Developments Ltd | Construction | 2020 |
| Artichoke Media Limited | Information & communication | 2023 |
| Articulate Group Limited | Administrative & support | 1986 |
| Articulate Technology Limited | Information & communication | 2011 |
| Artifact Automotive Limited | Wholesale & retail | 2024 |
| Artificial Grass Maintenance Limited | Administrative & support | 2005 |
| Artificial Intelligence Managed Services Limited | Information & communication | 2025 |
| Artificially Ltd | Wholesale & retail | 2020 |
| Artio Projects CIC | Professional & scientific | 2026 |
| Artiskov Ltd | Transport & logistics | 2019 |
| Artist Touch Ltd | Other services | 2018 |
| Artixelon Group Ltd | Information & communication | 2020 |
| Artoys Ltd | Wholesale & retail | 2025 |
| Artruck Ltd | Transport & logistics | 2015 |
| Artu Solutions Ltd | Construction | 2025 |
| Artur Electrician Ltd | Construction | 2021 |
| Arturas&Transport Ltd | Transport & logistics | 2017 |
| Arty Mobile Motor Mechs Limited | Wholesale & retail | 2025 |
| Arunmylan Limited | Professional & scientific | 2019 |
| Arunys Ltd | Transport & logistics | 2018 |
| Arwac Limited | Manufacturing | 2018 |
| Arwen Design and Development Limited | Extraterritorial | 1988 |
| ARX MEA Limited | Real estate | 2026 |
| Arya 2019 Ltd | Hospitality | 2023 |
| Arya Equity Ltd | Real estate | 2023 |
| AS Arboriculture Ltd | Administrative & support | 2023 |
| AS Controls Ltd | Wholesale & retail | 2013 |
| AS GD Deeping Limited | Hospitality | 2024 |
| AS GD Thurlby Limited | Hospitality | 2024 |
| AS Optics Ltd | Health & social care | 2024 |
| AS Roofing & Property Maintenance Ltd | Construction | 2025 |
| AS Vehicle Group Ltd | Wholesale & retail | 2022 |
| As.Delta Holding LLP | | 2026 |
| ASA Abode Ltd | Real estate | 2024 |
| ASA Motoring Group Ltd | Wholesale & retail | 2026 |
| Asad Arif Consultant Ltd | Administrative & support | 2019 |
| Asad Parvaiz Ltd | Health & social care | 2023 |
| Asanteman Market Limited | Wholesale & retail | 2026 |
| Asantepharma Limited | Health & social care | 2024 |
| Asap City Clearance Services Ltd | Transport & logistics | 2022 |
| Asasa Group Ltd | Professional & scientific | 2023 |
| ASB Air Conditioning Limited | Construction | 2008 |
| ASC Construction Services (UK) Limited | Professional & scientific | 2021 |
| Ascendancy.Tech Limited | Information & communication | 2023 |
| Ascensionx Ltd | Professional & scientific | 2026 |
| Ascensys Ltd | Professional & scientific | 2002 |
| Ascent Holding Services Ltd | Professional & scientific | 2022 |
| Ascent Residential Developments Limited | Construction | 2010 |
| Ascommerical Ltd | Real estate | 2025 |
| Ascott Electrical Installations Limited | Construction | 2019 |
| Asel Healthcare Ltd | Health & social care | 2020 |
| Asguard ITG Ltd | Wholesale & retail | 2026 |
| ASH Architecture and Design Ltd | Professional & scientific | 2025 |
| ASH House Consulting Services Limited | Professional & scientific | 2025 |
| ASH Investment Services Ltd | Households | 2024 |
| ASH School Transport Ltd | Transport & logistics | 2025 |
| Asha Homes Ltd | Construction | 2022 |
| Ashah KRD Ltd | Other services | 2025 |
| Ashbarr Limited | Real estate | 2002 |
| Ashbeach Homes Limited | Construction | 2019 |
| Ashbrook Heritage Limited | Wholesale & retail | 2024 |
| Ashbrooke Properties Limited | Real estate | 2020 |
| Ashbury Thurcroft Limited | Wholesale & retail | 2012 |
| Ashby Consulting Group Limited | Professional & scientific | 2025 |
| Ashchurch (ST Davids) Residents Company Limited | Households | 2003 |
| Ashcroft Distribution Ltd | Wholesale & retail | 2019 |
| Ashford Real Estate Ltd | Real estate | 2025 |
| Ashley & Brown Textiles Limited | Wholesale & retail | 2013 |
| Ashman & Cornwell Services Ltd | Financial services | 2019 |
| Ashman Architects Ltd | Professional & scientific | 2015 |