| Atto Electric UK Ltd | Wholesale & retail | 2021 |
| Attryom Limited | Professional & scientific | 2009 |
| Atts Accountants Ltd | Professional & scientific | 2025 |
| Attwoodpsych Ltd | Health & social care | 2023 |
| Atum Investigations Ltd | Administrative & support | 2019 |
| ATV Properties LLP | | 2022 |
| ATW Collective Ltd | Financial services | 2025 |
| ATW Events Ltd | Professional & scientific | 2018 |
| ATW Properties (Atwp) Ltd | Real estate | 2021 |
| Atwan Medical Ltd | Health & social care | 2015 |
| Atwd Construction Ltd | Real estate | 2024 |
| Atwd Properties Ltd | Real estate | 2023 |
| Atyab Alkhaleej Trading Limited | Wholesale & retail | 2025 |
| Atyaf Al-Muntaha for Investment Ltd | Wholesale & retail | 2024 |
| Au-Chemi Ltd | Manufacturing | 2020 |
| Aubaltix Ltd | Transport & logistics | 2017 |
| Auberge Consultancy Limited | Administrative & support | 2018 |
| Auberge Education Ltd | Education | 2019 |
| Aubergine Cafe and Events C.I.C. | Hospitality | 2018 |
| Aubern Ltd | Professional & scientific | 2025 |
| Auburn FOX Limited | Wholesale & retail | 2020 |
| AUC Cars Trading Ltd | Wholesale & retail | 2025 |
| Auckland Group Holdings Ltd | Administrative & support | 2024 |
| Auckland Race Trux Limited | Manufacturing | 2002 |
| Auckland Security Services Limited | Administrative & support | 2024 |
| Auction Boutique Ltd | Real estate | 2015 |
| Aucto Media Ltd | Information & communication | 2025 |
| Audiama Ltd | Information & communication | 2022 |
| Audience Central Limited | Professional & scientific | 2018 |
| Audio Cave (Cardiff) Ltd | Wholesale & retail | 2017 |
| Audio Visual 365 Ltd | Administrative & support | 2019 |
| Audiophile Amps Ltd | Professional & scientific | 2016 |
| Audiowaves AVL Production Limited | Administrative & support | 2026 |
| Audivance Ltd | Information & communication | 2024 |
| Audrey Blooming Limited | Wholesale & retail | 2025 |
| Auer Limited | Transport & logistics | 2016 |
| Aufines Ltd | Information & communication | 2025 |
| Aufman Construction Ltd | Wholesale & retail | 2008 |
| Auga Cosmetics Ltd | Wholesale & retail | 2026 |
| Augensterng Ltd | Wholesale & retail | 2025 |
| Augmented Scale Limited | Administrative & support | 2026 |
| Augmenting Therapy CIC | Health & social care | 2025 |
| Auguried Ltd | Professional & scientific | 2026 |
| August 012 Ltd | Arts & recreation | 2012 |
| August Morgan Building Maintenance Ltd | Construction | 2025 |
| August Properties (Spain) Limited | Real estate | 1997 |
| AUI the Ship Ltd | Real estate | 2021 |
| Aujla & Sons Ltd | Administrative & support | 2017 |
| Aujlatek Ltd | Professional & scientific | 2025 |
| Auleather X Limited | Wholesale & retail | 2025 |
| Aumber Group Ltd | Wholesale & retail | 2021 |
| AUR Communication Limited | Construction | 2017 |
| Aura Bora Limited | Wholesale & retail | 2015 |
| Aura Essentials Ltd | Wholesale & retail | 2025 |
| Aura Knit Limited | Wholesale & retail | 2025 |
| Aura Properties Management Ltd | Real estate | 2020 |
| Aura Soul London Limited | Wholesale & retail | 2024 |
| Aura Techno Ltd | Wholesale & retail | 2024 |
| Aura Trade Mart Ltd | Wholesale & retail | 2026 |
| Aura Transport Limited | Transport & logistics | 2025 |
| Auraaspect Creations Ltd | Information & communication | 2024 |
| AURACART381 Limited | Wholesale & retail | 2025 |
| Auraframe Limited | Construction | 2019 |
| Auralex Services Ltd | Wholesale & retail | 2021 |
| Auralis Botanics Ltd | Agriculture & fishing | 2025 |
| Auratrade Worldwide Ltd | Wholesale & retail | 2025 |
| Aure Jewels Ltd | Wholesale & retail | 2025 |
| Aurea Global Clinic Ltd | Health & social care | 2026 |
| Aurea Investment Management Ltd | Financial services | 2015 |
| Aurea Libre Ltd | Information & communication | 2025 |
| Aurelia Corp. PC | | 2017 |
| Aurelia Optics Ltd | Professional & scientific | 2024 |
| Aurelian Attire Ltd | Wholesale & retail | 2025 |
| Aurelian Crossborder Ltd | Wholesale & retail | 2025 |
| Aurelian Partners Limited | Financial services | 2025 |
| Aurelian Sportswear Ltd | Wholesale & retail | 2025 |
| Aurelian Technologies Ltd | Information & communication | 2025 |
| Aurelijus Trader Ltd | Administrative & support | 2019 |
| Aurenic Ltd | Wholesale & retail | 2025 |
| Aurenstowe Limited | Manufacturing | 2023 |
| Aureon-New Ltd | Professional & scientific | 2026 |
| Aurescent Limited | Administrative & support | 2015 |
| Aureum Tigris International Ltd | Wholesale & retail | 2021 |
| Aurevia Artificial Intelligence Ltd | Information & communication | 2025 |
| Aurevia Capital Partners Limited | Financial services | 2025 |
| Aurex Apparel Limited | Extraterritorial | 2026 |
| Auriga Cleaning Services Limited | Administrative & support | 2019 |
| Aurix.Gg Limited | Other services | 2025 |
| Aurniox Ltd | Education | 2025 |
| Auro Energy Ltd | Information & communication | 2025 |
| Aurola Beauties (UK) Ltd | Administrative & support | 2025 |
| Aurora Artisanry Ltd | Wholesale & retail | 2025 |
| Aurora Beam Ltd. | Wholesale & retail | 2024 |
| Aurora Bridge E-Commerce Limited | Wholesale & retail | 2025 |
| Aurora Cloud Technology Limited | Information & communication | 2021 |
| Aurora Court Management (Barry) Limited | Households | 2006 |
| Aurora Glint Limited | Wholesale & retail | 2022 |
| Aurora HR Consultants Limited | Professional & scientific | 2025 |
| Aurora.In Ltd | Wholesale & retail | 2021 |
| Aurore & Friendz Ltd | Wholesale & retail | 2025 |