| Athavan Ltd | Administrative & support | 2017 |
| Athelstan Fulfilment Ltd | Wholesale & retail | 2025 |
| Athena (Leicester) Limited | Real estate | 2011 |
| Athena Advisory Solutions Ltd | Information & communication | 2022 |
| Athena Case Management Limited | Health & social care | 2014 |
| Athena Events Limited | Hospitality | 2012 |
| Athena Housing Solutions CIC | Hospitality | 2023 |
| Athenix Ltd | Wholesale & retail | 2024 |
| Atherton Transport Ltd | Transport & logistics | 2024 |
| Athlete Sport and Entertainment Group Ltd | Administrative & support | 2019 |
| Athletic Installations Ltd | Manufacturing | 2023 |
| Athlyt Ltd | Information & communication | 2025 |
| Athome Healthcare Services Ltd | Information & communication | 2025 |
| Athp Ltd | Professional & scientific | 2024 |
| Athwal Property Group Ltd | Real estate | 2022 |
| Athwal Taxi Ltd | Transport & logistics | 2023 |
| Atia R&I Limited | Financial services | 2023 |
| Atik Perfumes Ltd | Wholesale & retail | 2021 |
| Atimus Medical Limited | Information & communication | 2023 |
| Ativas Investment Limited | Administrative & support | 2016 |
| ATJ Motors Ltd | Wholesale & retail | 2018 |
| ATK GAS & Electric Limited | Construction | 2021 |
| Atke Ltd | Transport & logistics | 2025 |
| Atkinson Leah Limited | Real estate | 2001 |
| Atkinson Plumbing & Heating (Leics) Ltd | Construction | 2006 |
| Atlantex LP | | 2017 |
| Atlantic Fabrications Ltd | Manufacturing | 2011 |
| Atlantic Import Export Ltd | Wholesale & retail | 2018 |
| Atlantic Property Ltd | Real estate | 2019 |
| Atlantic Seafood UK Ltd | Hospitality | 2020 |
| Atlantic Securities Ltd | Wholesale & retail | 2025 |
| Atlantic Tech Consulting Ltd | Information & communication | 2025 |
| Atlantis Leicester Ltd | Hospitality | 2013 |
| Atlantis Property Investment Ltd | Real estate | 2019 |
| Atlas Boxing & Fitness Club Ltd | Education | 2024 |
| Atlas Business & Services Ltd | Professional & scientific | 2025 |
| Atlas Development Solutions Ltd | Real estate | 2010 |
| Atlas Electrical Contractors Limited | Construction | 2007 |
| Atlas Hotels (Bath) Limited | Hospitality | 1999 |
| Atlas Hotels (Bedford) Limited | Hospitality | 2002 |
| Atlas Hotels (Borrowings 2) Limited | Professional & scientific | 2007 |
| Atlas Hotels (Borrowings) Limited | Professional & scientific | 2006 |
| Atlas Hotels (Bristol North) Limited | Hospitality | 1998 |
| Atlas Hotels (Bristol Property) Limited | Hospitality | 1996 |
| Atlas Hotels (Cambridge 2) Limited | Hospitality | 2007 |
| Atlas Hotels (Chingford) Limited | Hospitality | 1999 |
| Atlas Hotels (Derby) Limited | Hospitality | 1997 |
| Atlas Hotels (Exeter) Limited | Hospitality | 1997 |
| Atlas Hotels (Glasgow) Limited | Hospitality | 1997 |
| Atlas Hotels (Greenwich) Limited | Hospitality | 1998 |
| Atlas Hotels (Group 1) Limited | Hospitality | 2003 |
| Atlas Hotels (Group 2) Limited | Hospitality | 1999 |
| Atlas Hotels (Group 3 Property) Limited | Hospitality | 1990 |
| Atlas Hotels (Group 4 Property 1) Limited | Hospitality | 1997 |
| Atlas Hotels (Group 4 Property 2) Limited | Hospitality | 1997 |
| Atlas Hotels (Inverness) Limited | Hospitality | 1998 |
| Atlas Hotels (Lincoln) Limited | Hospitality | 2006 |
| Atlas Hotels (Liverpool) Limited | Hospitality | 2007 |
| Atlas Hotels (Oldbury) Limited | Hospitality | 1997 |
| Atlas Hotels (Property and Trading) Limited | Professional & scientific | 2000 |
| Atlas Hotels (Property) Limited | Professional & scientific | 2006 |
| Atlas Hotels (Salford Quays) Limited | Hospitality | 1997 |
| Atlas Hotels (Stevenage) Limited | Hospitality | 2003 |
| Atlas Hotels (Stoke on Trent) Limited | Hospitality | 1998 |
| Atlas Hotels (Taunton) Limited | Hospitality | 1997 |
| Atlas Hotels (Trading) Limited | Hospitality | 2006 |
| Atlas Hotels (Warwick) Limited | Hospitality | 1997 |
| Atlas Hotels Group Limited | Professional & scientific | 2009 |
| Atlas Hotels Limited | Hospitality | 1996 |
| Atlas Interactive Digital Limited | Administrative & support | 2017 |
| Atlas Interactive Group Limited | Wholesale & retail | 1996 |
| Atlas Interactive Holdings Limited | Professional & scientific | 1996 |
| Atlas Interactive Management Limited | Administrative & support | 1991 |
| Atlas Interactive Premium Limited | Information & communication | 2001 |
| Atlas Multi Services Ltd | Transport & logistics | 2022 |
| Atlas OBC Ltd | Transport & logistics | 2026 |
| Atlas Planning Designs Ltd | Professional & scientific | 2023 |
| Atlas Properties (Leicester) Ltd | Real estate | 2020 |
| Atlas Retail Consultants Limited | Information & communication | 1998 |
| Atlas Telecom Network (UK) Limited | Extraterritorial | 1998 |
| Atlas Textiles Ltd. | Wholesale & retail | 1997 |
| Atlas Transport Group Ltd | Construction | 2026 |
| Atlas Travels Leicester Limited | Administrative & support | 2010 |
| Atlas Ventures Global Ltd | Wholesale & retail | 2025 |
| Atlasatelier Ltd | Manufacturing | 2026 |
| Atlasmotive Ltd | Information & communication | 2024 |
| Atlastravels.Co.Uk Leicester Ltd | Administrative & support | 2024 |
| Atlus Holdings Ltd | Financial services | 2024 |
| Atlus Ltd | Wholesale & retail | 2024 |
| ATM (Holdings) Limited | Extraterritorial | 1995 |
| ATM Automation Limited | Manufacturing | 1986 |
| ATM Engineering Limited | Manufacturing | 2024 |
| ATM Group Digital Services Ltd | Information & communication | 2016 |
| ATM Trustees Limited | Manufacturing | 2025 |
| Atma Consulting Ltd | Professional & scientific | 2019 |
| Atma Productions Limited | Information & communication | 2014 |
| Atmim Limited | Professional & scientific | 2011 |
| Atmiya Physiotherapy & Rehabilitation Clinic Ltd | Health & social care | 2024 |
| Atmiya Spares Ltd | Wholesale & retail | 2019 |
| ATN Management Services Ltd | Administrative & support | 2019 |