| Apple Safety Training Limited | Other services | 2023 |
| Apple Trans Limited | Transport & logistics | 2023 |
| Applied Insight (Doncaster) Limited | Administrative & support | 2012 |
| Applifting Ltd | Extraterritorial | 2020 |
| Applin Property Ltd | Real estate | 2019 |
| Applynow.Io Ltd | Professional & scientific | 2025 |
| Apprentis Systems Ltd | Information & communication | 2026 |
| April Bloom Limited | Professional & scientific | 2025 |
| APRIL68 Ltd | Extraterritorial | 2026 |
| APS Conect Ltd | Transport & logistics | 2026 |
| AQ Electrical Ltd | Construction | 2024 |
| Aqua Blinds Limited | Other services | 2003 |
| Aqua Chem Environmental Ltd | Administrative & support | 2007 |
| Aqua Fusion Media Limited | Information & communication | 2008 |
| Aqua Utilities Ltd | Construction | 2013 |
| Aquashop Limited | Extraterritorial | 2012 |
| Aquasteps Limited | Extraterritorial | 2012 |
| Aquatic Dream Inventions LP | | 2016 |
| Aquatrail Ltd | Wholesale & retail | 2025 |
| AR Concierge Ltd | Other services | 2025 |
| AR Electrical UK Contractors Ltd | Construction | 2026 |
| AR K9 Security Ltd | Administrative & support | 2026 |
| AR Quality Assured Ltd | Professional & scientific | 2017 |
| AR Raja Meat Limited | Wholesale & retail | 2025 |
| Arab Vision Ltd | Manufacturing | 2023 |
| Aragon UK Investments Ltd | Real estate | 2025 |
| ARB Consultancy Limited | Information & communication | 2007 |
| ARB Drivers Limited | Transport & logistics | 2019 |
| Arba Developments Limited | Professional & scientific | 2014 |
| Arba Dukeries Kirkby Limited | Construction | 2024 |
| Arba Ground Trading Company Limited | Construction | 2016 |
| Arba Residential Limited | Real estate | 2021 |
| Arber Blue Limited | Real estate | 2024 |
| Arberry Architectural Services Ltd | Professional & scientific | 2020 |
| Arbitrium Wealth Management Ltd | Extraterritorial | 2019 |
| Arborix Ltd | Administrative & support | 2016 |
| Arbrit Lifting and Training Solutions Limited | Education | 2016 |
| ARC Engineering Consultants Ltd | Extraterritorial | 2015 |
| ARC Property Holdings Limited | Real estate | 2001 |
| Arcade Planet Limited | Manufacturing | 2023 |
| Arcadian Homes Limited | Real estate | 2021 |
| Arcan Pizza Limited | Hospitality | 2025 |
| Arceus Ltd | Wholesale & retail | 2024 |
| Arch and Align Ltd | Other services | 2025 |
| Archangelo Music Ltd | Information & communication | 2022 |
| Archers Commercials Limited | Wholesale & retail | 2005 |
| Archie Pearce Racing Ltd | Arts & recreation | 2025 |
| Architectural Environments Ltd | Professional & scientific | 2008 |
| Architecture Box Limited | Professional & scientific | 2010 |
| Archplan Engineers Ltd | Administrative & support | 2007 |
| Arcova Protection Limited | Information & communication | 2025 |
| Arctic Heat Fusion Ltd | Manufacturing | 2026 |
| ARD Trans Ltd | Transport & logistics | 2026 |
| Arda Estate Limited | Real estate | 2025 |
| Ardenpeak Digital Ltd | Extraterritorial | 2026 |
| Ardent Allround Services LLP | | 2016 |
| Ardent Glazing Limited | Professional & scientific | 2021 |
| Ardent Investigative Solutions Limited | Administrative & support | 2019 |
| Ardj Investment Limited | Financial services | 2006 |
| Ardpoll Installation Services Limited | Construction | 2016 |
| Ardwick Property Limited | Real estate | 2019 |
| Areej Saghir Ltd | Wholesale & retail | 2024 |
| Arefurbs Ltd | Wholesale & retail | 2026 |
| Areg Investment Ltd. | Financial services | 2018 |
| Arelko Properties Limited | Real estate | 2025 |
| Aremda Group Ltd | Administrative & support | 2021 |
| Arena Caffe Ltd | Hospitality | 2021 |
| Arenas Mini Market Limited | Wholesale & retail | 2026 |
| Ares Couriers Ltd | Transport & logistics | 2020 |
| ARG Care Services Ltd | Health & social care | 2023 |
| Argent Catering Solutions (UK) Ltd | Hospitality | 2013 |
| Argin Trading Ltd | Wholesale & retail | 2009 |
| Argo Tractors Machinery Limited | Wholesale & retail | 2025 |
| Argo Tree Specialists Limited | Agriculture & fishing | 2020 |
| Argonaut Risk Ltd | Administrative & support | 2024 |
| Ari.Carriage Ltd | Transport & logistics | 2023 |
| Aria EXH Limited | Real estate | 2024 |
| Aries Lighting Ltd | Wholesale & retail | 2020 |
| Aries Networks Limited | Information & communication | 1991 |
| ARK Innovations Ltd | Professional & scientific | 2020 |
| Arka Trans Ltd | Transport & logistics | 2023 |
| ARL Car & Commercial Ltd | Wholesale & retail | 2023 |
| Armadex Explosion Protection Ltd | Manufacturing | 2022 |
| Armand’S Auto Ltd | Wholesale & retail | 2026 |
| Armstrong Diamond Ltd | Real estate | 2013 |
| Armstrong Healthcare Ltd | Health & social care | 2022 |
| Armstrong's Butchers Limited | Wholesale & retail | 2021 |
| Armthorpe Accountancy Services Limited | Professional & scientific | 2006 |
| Armthorpe Autoworks Ltd | Wholesale & retail | 2021 |
| Armthorpe Carwash Doncaster Ltd | Other services | 2019 |
| Armthorpe Community Library Limited | Arts & recreation | 2014 |
| Armthorpe Day Care Nursery Limited | Health & social care | 2004 |
| Armthorpe Falconry Limited | Agriculture & fishing | 2010 |
| Armthorpe Glass Limited | Construction | 1974 |
| Armthorpe Shaw Wood Academy Limited | Education | 2012 |
| Armthorpe Skip Hire Ltd | Water & waste | 2025 |
| Armthorpe Skips Ltd | Water & waste | 2011 |
| Armthorpe Supplies Ltd | Wholesale & retail | 2021 |
| Armthorpe Vape Shop Limited | Wholesale & retail | 2016 |
| ARN Diagnostics Limited | Wholesale & retail | 2013 |