| Art Media Advertising Limited | Information & communication | 2023 |
| Art of Everything Limited | Other services | 2021 |
| Art Sync Limited | Arts & recreation | 2024 |
| Art&Co Limited | Professional & scientific | 2025 |
| Art-Weld Ltd | Construction | 2014 |
| ART2000 Ltd | Construction | 2013 |
| Artcon Ltd | Construction | 2014 |
| Arte Limited | Real estate | 2025 |
| Artec Boxer UK Ltd | Manufacturing | 2023 |
| Artech Bristol Ltd | Wholesale & retail | 2024 |
| Artek FOX Ltd | Professional & scientific | 2025 |
| Artelier Arts Limited | Arts & recreation | 2012 |
| Artelier Properties Limited | Real estate | 2022 |
| Artemia Press Ltd | Information & communication | 2013 |
| Arteos GP Limited | Administrative & support | 2006 |
| Artesia Consulting Limited | Professional & scientific | 2008 |
| Artesty Ltd | Wholesale & retail | 2022 |
| Arthur Cameron Holdings Ltd | Real estate | 2025 |
| Arthur David (Food With Service) Limited | Wholesale & retail | 1986 |
| Arthur E Davey & Sons Limited | Other services | 2013 |
| Arthur T. Miller Limited | Real estate | 1961 |
| Arthur's Estates Limited | Real estate | 2024 |
| Artichoke Wholefoods Ltd | Wholesale & retail | 2021 |
| Articulate Digital Ltd | Information & communication | 2018 |
| Artificial Intelligence Leadership Ltd | Information & communication | 2025 |
| Artificial Intelligence Machines Ltd | Information & communication | 2017 |
| Artifusion Ltd | Construction | 2023 |
| Artigiano Winford Arms Ltd | Hospitality | 2023 |
| Artingstalls (Butchers) Limited | Wholesale & retail | 2011 |
| Artis Dice Pizza Ltd | Hospitality | 2022 |
| Artis Recruitment Ltd | Administrative & support | 2007 |
| Artisan Associates Limited | Construction | 2011 |
| Artisan Design Studio Limited | Administrative & support | 2018 |
| Artisan Garden Store Limited | Wholesale & retail | 2025 |
| Artisan Landscapes Limited | Administrative & support | 2013 |
| Artist Studios Ltd | Arts & recreation | 2015 |
| Artistic Blinds (Retail) Limited | Wholesale & retail | 2018 |
| Artistic Curry Ltd | Hospitality | 2025 |
| Artistic Stars Limited | Arts & recreation | 2008 |
| Artivisual Media Ltd | Other services | 2017 |
| Artizan Bath Limited | Professional & scientific | 2006 |
| Artizen Ltd | Extraterritorial | 2023 |
| Artlings Bristol LLP | | 2022 |
| Artrageous Creative Limited | Wholesale & retail | 2013 |
| Artryx Ltd | Wholesale & retail | 2022 |
| Arts Afterschool Ltd | Health & social care | 2024 |
| Arts in Development Limited | Professional & scientific | 2010 |
| Artsci International Ltd | Arts & recreation | 2019 |
| Artspace Lifespace Enterprises Limited | Arts & recreation | 2016 |
| Artstud Ltd | Professional & scientific | 2018 |
| Artus Windows, Doors & Conservatories Limited | Construction | 2014 |
| Artvedia Ltd | Other services | 2018 |
| Artvik Trans Ltd. | Transport & logistics | 2017 |
| Artworking Web Design Ltd | Professional & scientific | 2012 |
| Artworks Solutions (EOT) Limited | Financial services | 2023 |
| Artworks Solutions Limited | Manufacturing | 2002 |
| Arum Global Limited | Financial services | 2017 |
| Arum Systems Ltd | Information & communication | 1998 |
| Arun IFV Consulting Ltd | Professional & scientific | 2025 |
| Arun Ionut Ltd | Wholesale & retail | 2022 |
| Arunseva Ltd | Real estate | 2018 |
| ARV Club Limited | Arts & recreation | 2022 |
| ARV Solutions Contracts Limited | Administrative & support | 2011 |
| ARV Solutions Limited | Administrative & support | 2014 |
| Arven Golf Ltd | Manufacturing | 2026 |
| Arvey Property Ltd | Real estate | 2021 |
| Arvy Logistics Ltd | Transport & logistics | 2025 |
| ARW Building Services (South West) Ltd | Construction | 2015 |
| Arwc Consulting Ltd | Real estate | 2008 |
| Arweb Limited | Information & communication | 2024 |
| ARX Engineers Ltd | Professional & scientific | 2025 |
| Arya Consulting Limited | Professional & scientific | 2008 |
| Aryan Oral Care Ltd | Health & social care | 2015 |
| Aryan PM Properties Ltd | Real estate | 2021 |
| Aryosh Property Investment Ltd | Real estate | 2024 |
| AS Change Services Ltd | Information & communication | 2025 |
| AS Coaching Ltd | Professional & scientific | 2021 |
| AS Conveyance Ltd | Transport & logistics | 2022 |
| AS IT IS TV Limited | Transport & logistics | 2018 |
| AS Networking Ltd | Information & communication | 2015 |
| AS One Horticulture Ltd | Agriculture & fishing | 2024 |
| AS Precision Inspections Limited | Professional & scientific | 2025 |
| AS Roofing & Maintenance Limited | Construction | 2013 |
| AS Well Health Ltd | Health & social care | 2025 |
| ASA Global Health Limited | Health & social care | 2021 |
| ASA Group Atlantic Ltd | Wholesale & retail | 2025 |
| ASA Prime Living Ltd | Real estate | 2024 |
| Asabell Limited | Administrative & support | 2003 |
| Asad&Rayhan Spuds Limited | Hospitality | 2025 |
| Asana Software UK Limited | Information & communication | 2019 |
| Asander Group Limited | Financial services | 2026 |
| Asandex Healthcare Limited | Health & social care | 2023 |
| Asante Property Company Ltd | Real estate | 2023 |
| Asante Sana Ltd | Construction | 2009 |
| Asap Crep Ltd | Wholesale & retail | 2025 |
| Asap Vape Limited | Wholesale & retail | 2021 |
| ASAP13 Limited | Wholesale & retail | 2026 |
| Asapp Limited | Information & communication | 2016 |
| Asasa Property Ltd | Real estate | 2023 |
| Asbestosurv Ltd | Extraterritorial | 2026 |