| Apache Auctions Ltd | Wholesale & retail | 2017 |
| Apadapartments Limited | Real estate | 2016 |
| APE Pilot Limited | Other services | 2020 |
| Aperiodic Metastructures Ltd | Professional & scientific | 2026 |
| Apex Automotive Group Ltd | Wholesale & retail | 2026 |
| Apex Court Freehold Limited | Households | 2013 |
| Apex Developers Limited | Real estate | 1999 |
| Apex Drones Ltd | Administrative & support | 2026 |
| Apex ENT Ltd | Health & social care | 2017 |
| Apex Guild Awards Ltd | Professional & scientific | 2025 |
| Apex Management and Services Ltd | Administrative & support | 2026 |
| Apex Probuild Ltd | Construction | 2023 |
| Apex Security Limited | Administrative & support | 2002 |
| Apex Sprayed Concrete & Construction Ltd | Manufacturing | 2021 |
| Apex Vape & CBD Limited | Wholesale & retail | 2019 |
| Aphestia Ltd | Real estate | 2023 |
| Aphrodite Beauty Salon Limited | Other services | 2007 |
| APM Lining Ltd | Construction | 2026 |
| Apollo Heating Limited | Construction | 2020 |
| Apollo Olympus Capital Limited | Construction | 2025 |
| Apotek Limited | Wholesale & retail | 2008 |
| Appetites Gourmet Ltd | Hospitality | 2008 |
| Appius International Ltd | Information & communication | 1997 |
| Appliance Protection Line Ltd | Other services | 2019 |
| Appliance Reliance Ltd | Other services | 2018 |
| Applianceserve Ltd | Other services | 2014 |
| Applications Platforms Limited | Information & communication | 2018 |
| Applied Shapes Limited | Manufacturing | 2012 |
| Appreciable Cleaning Private Limited | Administrative & support | 2025 |
| Approved Roofing Specialists Ltd | Construction | 2019 |
| Approved Technology Limited | Manufacturing | 2008 |
| Aprg Properties Ltd | Real estate | 2025 |
| April Court (Bournemouth) Freehold Limited | Households | 2000 |
| April MAY Morgan Limited | Health & social care | 2024 |
| Apsley Court RTM Company Limited | Households | 2023 |
| APT Telemarketing Limited | Administrative & support | 2009 |
| Aptec Technologies Limited | Manufacturing | 1995 |
| APX Motors Ltd | Wholesale & retail | 2025 |
| Aqsa Grill Ltd | Hospitality | 2024 |
| Aqua Investments (Lymington) Ltd | Construction | 2020 |
| Aqua KOI Limited | Wholesale & retail | 2015 |
| Aqua Skin Clinic Limited | Health & social care | 2017 |
| Aqua Sports Yachting Limited | Arts & recreation | 2004 |
| Aqua-Tight Solutions Ltd | Other services | 2019 |
| AQUA19 Ltd | Other services | 2024 |
| AQUA85 Ltd | Wholesale & retail | 2022 |
| Aquapole Cleaning Limited | Administrative & support | 2005 |
| Aquapole Properties Ltd | Real estate | 2020 |
| Aquarius (Southbourne) Management Company Ltd | Households | 2020 |
| Aquila Accountants Ltd | Professional & scientific | 2015 |
| Aquila Freehold Limited | Households | 2021 |
| AR Pensions & Wellbeing Consulting Ltd | Administrative & support | 2020 |
| AR UK Visa Ltd | Professional & scientific | 2018 |
| ARA Energy Group Ltd | Construction | 2024 |
| Arabellas Hair and Beauty Ltd | Other services | 2022 |
| Aram Developments Ltd | Construction | 2018 |
| Arancor Ltd | Professional & scientific | 2017 |
| ARB KIT Hire Ltd | Administrative & support | 2020 |
| Arbc Ltd | Information & communication | 2018 |
| Arbor Grind Limited | Administrative & support | 2014 |
| Arbour Umbrellas Ltd | Construction | 2022 |
| ARC Ecological Services Limited | Professional & scientific | 2011 |
| ARC Energy Ltd | Construction | 2025 |
| ARC Project Finance Limited | Financial services | 2021 |
| Arcadia Business Intelligence Ltd | Professional & scientific | 2012 |
| Arcadia Decorating Ltd | Construction | 2015 |
| Arcadias ARK Holdings Ltd | Real estate | 2022 |
| Arcai Limited | Information & communication | 2025 |
| Arch Scene Limited | Administrative & support | 1999 |
| Archer Plumbing and Heating Engineers Ltd | Construction | 2021 |
| Archos Investments Limited | Real estate | 2018 |
| Archos Lettings and Management Ltd | Real estate | 2026 |
| Archway Wrought Iron Limited | Manufacturing | 2019 |
| Arcturus Consulting Partners Ltd | Administrative & support | 2025 |
| Arden Property Consultants Ltd | Real estate | 2017 |
| Ardor Projects Ltd | Construction | 2023 |
| Arelia Project Solutions Ltd | Information & communication | 2024 |
| Arenco Trading Ltd | Wholesale & retail | 2017 |
| Arenitos Ltd | Real estate | 2016 |
| Argent Homes Limited | Construction | 2019 |
| Argo Capital Partners Limited | Financial services | 2018 |
| Argon Freehold Ltd | Real estate | 2020 |
| Argonaut Powder Coating Limited | Construction | 1988 |
| Argyle Mansions (Boscombe) Limited | Households | 1958 |
| Argyll Flat Management Company Limited | Households | 1987 |
| Aria Versatile Limited | Professional & scientific | 2023 |
| Aria Wild Versatile Ltd | Professional & scientific | 2024 |
| Ariadne's Gold Publishing Ltd | Information & communication | 2022 |
| Ariahs Spices Ltd | Hospitality | 2025 |
| Aris Jewellers Limited | Manufacturing | 2011 |
| Aristo Health Ltd | Financial services | 2019 |
| Arjuna Fencing Ltd | Construction | 2019 |
| ARK Bay Limited | Real estate | 2024 |
| ARK Developments (Poole) Limited | Construction | 2018 |
| ARK Subsea Services Limited | Professional & scientific | 2022 |
| Arkik Services Ltd | Hospitality | 2026 |
| Arks Construction Ltd | Construction | 2016 |
| Arks Lets Ltd | Real estate | 2024 |
| ARL Cars Limited | Wholesale & retail | 2015 |
| Arlan Holdings Limited | Financial services | 2020 |