| Atif Group Ltd | Financial services | 2024 |
| Atiforia Ltd | Wholesale & retail | 2024 |
| Atijulya Care Limited | Health & social care | 2022 |
| Atik Contractors Limited | Professional & scientific | 2019 |
| Atillier Boutique Ltd | Wholesale & retail | 2025 |
| ATJ Consultancy Ltd | Professional & scientific | 2025 |
| ATJ Logistic Ltd | Wholesale & retail | 2025 |
| ATJ Ventures Ltd | Real estate | 2019 |
| ATK Essentials Ltd | Wholesale & retail | 2023 |
| ATK Investment Holdings Limited | Financial services | 2025 |
| ATK Investment Property Limited | Real estate | 2024 |
| ATK Services Ltd | Transport & logistics | 2017 |
| Atkay Services Limited | Wholesale & retail | 2015 |
| Atkins Building Services (Manchester) Limited | Construction | 1999 |
| Atkins Flynn Ltd | Professional & scientific | 2015 |
| Atkinson Road Flats Ltd | Real estate | 2021 |
| Atkinson Stairlifts Limited | Wholesale & retail | 2025 |
| Atkom Limited | Public administration | 2019 |
| ATL Supplies Ltd | Wholesale & retail | 2026 |
| ATL UK Enterprises Limited | Agriculture & fishing | 2019 |
| Atla Estates Limited | Real estate | 2025 |
| Atla Projects Ltd | Manufacturing | 2025 |
| Atla Services Limited | Education | 2014 |
| Atlafamily Limited | Financial services | 2025 |
| Atlam Property Services Ltd | Real estate | 2025 |
| Atlanta Building Solutions Ltd | Construction | 2018 |
| Atlantic Bay Hotel (Woolacombe) Limited | Real estate | 2016 |
| Atlantic Bay Hotel (Woolacombe) Management Limited | Hospitality | 2016 |
| Atlantic Bays Holiday Park Limited | Real estate | 2022 |
| Atlantic Chicken Ltd | Hospitality | 2025 |
| Atlantic Fish Bar Limited | Hospitality | 1994 |
| Atlantic Fish Bar Northenden Ltd | Hospitality | 2022 |
| Atlantic Healthcare PLC | Professional & scientific | 2006 |
| Atlantic Insight Limited | Professional & scientific | 2019 |
| Atlantic Light Ltd | Real estate | 2025 |
| Atlantic Media Rights Limited | Information & communication | 2011 |
| Atlantic Paragon Estates Ltd | Professional & scientific | 2022 |
| Atlantic Radio Group Limited | Information & communication | 2024 |
| Atlantic Shield Ltd | Financial services | 2025 |
| Atlantic Steel Processing Limited | Wholesale & retail | 2001 |
| Atlantic Timber Holdings Limited | Financial services | 2015 |
| Atlantic Trading (Worldwide) Limited | Professional & scientific | 2024 |
| Atlantica Estates Limited | Professional & scientific | 1997 |
| Atlantico Investments Limited | Real estate | 2002 |
| Atlantim KAR Limited | Administrative & support | 2025 |
| Atlantis Clothing Company Ltd | Wholesale & retail | 2007 |
| Atlantis Event Medical Services Ltd | Health & social care | 2019 |
| Atlantis Innovation Ltd | Professional & scientific | 2021 |
| Atlantis Services Ltd | Other services | 2007 |
| Atlantis Technology Services Ltd | Information & communication | 2022 |
| Atlantix Construction Ltd | Construction | 1999 |
| Atlantix Developments Ltd | Extraterritorial | 2008 |
| Atlas & Clover Property Management Ltd | Real estate | 2025 |
| Atlas Account Consultancy Limited | Construction | 2021 |
| Atlas Artisans Ltd | Wholesale & retail | 2025 |
| Atlas Company Management Ltd | Wholesale & retail | 2025 |
| Atlas Construction and Renovation Limited | Construction | 2023 |
| Atlas Crown Trading Ltd | Wholesale & retail | 2025 |
| Atlas Development MCR Ltd | Real estate | 2022 |
| Atlas Electronics Ltd | Wholesale & retail | 2025 |
| Atlas Estates MCR Ltd | Real estate | 2026 |
| Atlas for General Trading Limited | Extraterritorial | 2026 |
| Atlas for International Services Limited | Extraterritorial | 2026 |
| Atlas for International Trading & Services Limited | Extraterritorial | 2026 |
| Atlas for Investment & Trading Ltd | Extraterritorial | 2026 |
| Atlas for Trading Limited | Extraterritorial | 2026 |
| Atlas Forge Records Limited | Information & communication | 2025 |
| Atlas Group of Companies Ltd | Construction | 2025 |
| Atlas Heating Supplies Limited | Wholesale & retail | 1981 |
| Atlas Home Care Ltd | Public administration | 2022 |
| Atlas Home Group Ltd | Hospitality | 2025 |
| Atlas Home Services Limited | Real estate | 2023 |
| Atlas ICS Design Ltd | Manufacturing | 2022 |
| Atlas Incorporation Ltd | Financial services | 2026 |
| Atlas Industrial Group Limited | Wholesale & retail | 2026 |
| Atlas International Trading Limited | Extraterritorial | 2026 |
| Atlas Law Limited | Professional & scientific | 2012 |
| Atlas Lifts Limited | Manufacturing | 2016 |
| Atlas Marketplace Ltd | Wholesale & retail | 2024 |
| Atlas Nexus Urbanism Ltd | Professional & scientific | 2026 |
| Atlas Performance Labs Ltd | Information & communication | 2026 |
| Atlas Personal Training Limited | Other services | 2026 |
| Atlas Placement Group Ltd | Professional & scientific | 2025 |
| Atlas Property Business Limited | Real estate | 2024 |
| Atlas Property Group Limited | Real estate | 2020 |
| Atlas Property Partners Limited | Real estate | 2025 |
| Atlas Risk Management Limited | Financial services | 2001 |
| Atlas Tech Solutions Ltd | Information & communication | 2024 |
| Atlas Vehicle Sales Ltd | Wholesale & retail | 2023 |
| Atleys Limited | Construction | 2024 |
| Atli Ventures Ltd | Information & communication | 2024 |
| Atlon Professional Services Ltd | Information & communication | 2025 |
| ATM Building Services (UK) Limited | Construction | 2005 |
| ATM Communications Limited | Information & communication | 2001 |
| ATM Engineering Services Ltd | Transport & logistics | 2000 |
| ATM General Trading Ltd | Wholesale & retail | 2024 |
| ATM Roofing Services Ltd | Construction | 2025 |
| Atmd Trading Ltd | Wholesale & retail | 2020 |
| Atmm Tech Ltd | Transport & logistics | 2026 |
| Atmos International Limited | Manufacturing | 1995 |