| AA Starz Ltd | Wholesale & retail | 2022 |
| AA Stay Ltd | Real estate | 2022 |
| AA Style Ltd | Wholesale & retail | 2024 |
| Aa&S Plumbing&Heating Service Ltd | Construction | 2021 |
| AA2 Letts & Mgmt Ltd | Real estate | 2024 |
| AA2 Providence Ltd | Financial services | 2024 |
| AAI Investments Ltd | Real estate | 2018 |
| Aamir & Ahmed Ltd | Hospitality | 2020 |
| Aapir ELECTRICAL24/7 Limited | Construction | 2025 |
| Aardvark Property Services Limited | Wholesale & retail | 2018 |
| Aarh Limited | Wholesale & retail | 2013 |
| Aaria Holdings Ltd | Real estate | 2019 |
| Aarivinfotech Ltd | Information & communication | 2025 |
| Aars Properties Ltd | Real estate | 2024 |
| Aarush Estates Limited | Real estate | 2026 |
| Aasend Solutions Ltd | Education | 2025 |
| Aasri Ltd | Real estate | 2024 |
| AATHMY1 Agency Ltd | Information & communication | 2024 |
| Aathvika Transport Limited | Transport & logistics | 2018 |
| Aayubo Limited | Professional & scientific | 2025 |
| Aayushree Estate Ltd | Real estate | 2020 |
| AB & AJ Ltd | Wholesale & retail | 2019 |
| AB Abundance Ltd | Wholesale & retail | 2024 |
| AB Consulting 2020 Limited | Professional & scientific | 2020 |
| AB Health Solutions Limited | Health & social care | 2014 |
| AB Management Consulting Ltd | Professional & scientific | 2022 |
| AB Transport AYL Limited | Transport & logistics | 2026 |
| Abacus Associates (UK) Limited | Professional & scientific | 2005 |
| Abaza Motors Ltd | Wholesale & retail | 2023 |
| Abbeybridge Limited | Real estate | 2022 |
| Abbeydale Partners LLP | | 2018 |
| Abbot Fixing Systems Limited | Construction | 1993 |
| Abbot Technical Services Limited | Manufacturing | 1998 |
| Abbott Designs Limited | Information & communication | 2005 |
| ABC Taxis 247 Limited | Transport & logistics | 2021 |
| ABC Taxis of Aylesbury Ltd | Transport & logistics | 2016 |
| ABI Entertainment Limited | Arts & recreation | 2023 |
| ABI Tuition Limited | Education | 2013 |
| Abigail Properties Limited | Real estate | 2025 |
| Ability Lifts Limited | Construction | 2004 |
| Abington Enterprises Limited | Professional & scientific | 1991 |
| Able Panda Consultancy Ltd | Professional & scientific | 2021 |
| Abney Management Services Ltd | Professional & scientific | 2012 |
| Abode Realty Ltd | Real estate | 2024 |
| Abode Scaffolding Ltd | Construction | 2009 |
| About That Growth Ltd | Professional & scientific | 2024 |
| ABR Adven Ltd | Wholesale & retail | 2018 |
| Abros Digital Ltd | Wholesale & retail | 2026 |
| Absolute Cleaning Solutions Ltd | Administrative & support | 2024 |
| Absolute Rehabilitation and Healthcare Services Limited | Information & communication | 2016 |
| Absolute Zero Air Conditioning Limited | Construction | 1996 |
| ABU Haashir Perfumes Ltd | Manufacturing | 2025 |
| Abusua Casa Limited | Real estate | 2025 |
| ABV (Management) Bicester Limited | Real estate | 2008 |
| Abzcoaching Ltd | Education | 2025 |
| AC Electrical Services (Quainton) Ltd | Construction | 2022 |
| Acar 2 Go Ltd | Wholesale & retail | 2007 |
| ACAR2GO Holdings Ltd | Financial services | 2021 |
| Acbl Consultancy Limited | Professional & scientific | 2023 |
| Accelerated Learning Systems Limited | Information & communication | 1976 |
| Accessible Cars Ltd | Transport & logistics | 2024 |
| Accessit Cloud Solutions Limited | Administrative & support | 2016 |
| Accessit Data (Holdings) Ltd | Extraterritorial | 2007 |
| Accessit Data Ltd | Administrative & support | 2004 |
| Accfm Limited | Energy | 2003 |
| Accident Intelligence (Newcastle) Limited | Wholesale & retail | 2025 |
| Accident Intelligence Holdings Limited | Financial services | 2025 |
| Acco Brands Europe Holding LP | | 2005 |
| Acco Brands Europe Limited | Professional & scientific | 2005 |
| Acco Company Limited | Extraterritorial | 1969 |
| Acco Europe Finance LP | | 2005 |
| Acco Europe Limited | Professional & scientific | 1987 |
| Acco Europe Trustee Company Limited | Financial services | 1969 |
| Acco UK Finance 1 Limited | Financial services | 2025 |
| Acco UK Finance 2 Limited | Financial services | 2025 |
| Acco UK Holdings 1 Limited | Financial services | 2025 |
| Acco UK Holdings 2 Limited | Financial services | 2025 |
| Acco UK Limited | Manufacturing | 1924 |
| Acco-Rexel Group Services Limited | Professional & scientific | 1950 |
| Accofrisk Ltd | Wholesale & retail | 1985 |
| Accomplished Scientific Communications Ltd | Professional & scientific | 2016 |
| Accountabel Ltd | Professional & scientific | 2014 |
| Accounting H4P Limited | Professional & scientific | 2022 |
| Accountlly Limited | Professional & scientific | 2026 |
| Accuratear Ltd | Health & social care | 2019 |
| Accurocare (Management) Limited | Financial services | 2023 |
| Accurocare Ebbw Vale Limited | Health & social care | 2023 |
| Accurocare ST. John's Home Limited | Health & social care | 2015 |
| Accurocare Wrexham Limited | Health & social care | 2022 |
| Accurocare Zoar Care Home Limited | Health & social care | 1988 |
| Ace Alps Ltd | Wholesale & retail | 2026 |
| Ace Car Recovery Services Ltd | Wholesale & retail | 2014 |
| Ace Drone Services Ltd | Professional & scientific | 2026 |
| Ace of Plumbing Ltd | Construction | 2024 |
| Ace of Shaves Ltd | Other services | 2020 |
| Acee Marketing Solutions Ltd | Professional & scientific | 2025 |
| Acetech Electrical South East Ltd | Construction | 2015 |
| ACG Garage Ltd | Wholesale & retail | 2023 |
| ACG PUB Company Ltd | Hospitality | 2017 |
| Achievers Consultancy and Training Limited | Professional & scientific | 2000 |