| Amped Vision Ltd | Information & communication | 2026 |
| Amritsari Dhaba Ltd | Hospitality | 2025 |
| AMS Staffs Ltd | Extraterritorial | 2024 |
| AMY Jasmine Aesthetics Ltd | Other services | 2024 |
| AMZ Medical Solutions Ltd | Health & social care | 2018 |
| Anais Rossa Ltd | Wholesale & retail | 2026 |
| Analytics-Led Insight Ltd | Professional & scientific | 2025 |
| Anasma Greek Bakery Ltd | Hospitality | 2023 |
| Andra Developments Limited | Construction | 2002 |
| Andrew Gray Ltd | Health & social care | 2010 |
| Andrew J Jadczak Limited | Construction | 2016 |
| Andy's Delivery Ltd | Transport & logistics | 2026 |
| Anessa Children's Homes Ltd | Health & social care | 2024 |
| Angelo Michael Pomelli Limited | Wholesale & retail | 2024 |
| Angels Cuisine 1 and Africa Food Limited | Hospitality | 2025 |
| Anglia Holdings Ltd | Professional & scientific | 1991 |
| Anglo American Distributors Limited | Wholesale & retail | 1997 |
| Annabelle's Health and Welness Ltd | Other services | 2019 |
| Annacrievy Management Company Limited | Households | 2016 |
| ANT Charles Logistics Ltd | Transport & logistics | 2018 |
| Antec Design Solutions Limited | Professional & scientific | 2000 |
| Anthony Liddell DPD Ltd | Transport & logistics | 2026 |
| Anvil Engineering Limited | Agriculture & fishing | 2014 |
| AOD Fashions Limited | Manufacturing | 2024 |
| AOS Enterprise Ltd | Wholesale & retail | 2023 |
| AP Johnson Building Ltd | Construction | 2025 |
| Apache Communications Ltd | Hospitality | 2025 |
| Apedale Enterprises Limited | Administrative & support | 2012 |
| Apedale Properties Ltd | Real estate | 2020 |
| Apex Homes Midlands Ltd | Construction | 2024 |
| Apex Newcastle Loft Conversions and Extensions Limited | Construction | 2020 |
| APL Heating Limited | Construction | 2000 |
| Aplitic Apparel Ltd | Wholesale & retail | 2017 |
| Appgroup Development Ltd | Information & communication | 2025 |
| Apple Tree Town Ltd | Health & social care | 2019 |
| Applerise Limited | Hospitality | 1999 |
| APT Heating and Renewables Ltd | Construction | 2025 |
| APW Innovations Limited | Administrative & support | 2016 |
| AR Electrical Specialists Limited | Construction | 2012 |
| Arakis N Limited | Construction | 2025 |
| ARC Equestrian Ltd | Administrative & support | 2019 |
| Arcadia Amusements Ltd | Arts & recreation | 2016 |
| Arch Construction (1972) Ltd | Construction | 2025 |
| Ardeen Group Limited | Financial services | 2021 |
| Ardeen Ltd | Construction | 2020 |
| Arden Integration Limited | Construction | 2018 |
| Ardox Ltd | Wholesale & retail | 2025 |
| Arel Marketing Ltd | Professional & scientific | 2025 |
| Arena Athletics Ltd | Arts & recreation | 2026 |
| Arena Comet UK Ltd | Administrative & support | 2022 |
| Arena Games Ltd | Arts & recreation | 2026 |
| Arena Invest Ltd | Real estate | 2021 |
| Arena IP Ltd | Arts & recreation | 2026 |
| Arena Media Group Ltd | Arts & recreation | 2026 |
| Arena Partnerships Ltd | Arts & recreation | 2026 |
| ARG Agricultural Services Ltd | Agriculture & fishing | 2022 |
| Argyle Garage Limited | Administrative & support | 1961 |
| ARK Construction (1972) Ltd | Construction | 2025 |
| Armaans Indian Limited | Hospitality | 2024 |
| Armstrong Cleaning Services Limited | Administrative & support | 2025 |
| Armstrong Installations Ltd | Construction | 2026 |
| Armstrong Vehicle Recycling Ltd | Administrative & support | 2002 |
| Armstrongs & Armstrong Ltd | Health & social care | 2012 |
| Armstrongs Commercial Limited | Financial services | 2013 |
| Arnav & Advait Ltd | Health & social care | 2016 |
| Aromatics Limited | Wholesale & retail | 2005 |
| Arsala Shine Ltd | Wholesale & retail | 2025 |
| Arthur Super Food Ltd | Wholesale & retail | 2026 |
| Arunas Trader Ltd | Administrative & support | 2019 |
| Arvest Shop Limited | Wholesale & retail | 2024 |
| Asaphones Limited | Wholesale & retail | 2026 |
| Asdp Limited | Financial services | 2013 |
| Asem Properties Ltd | Real estate | 2024 |
| ASG Healthcare Limited | Real estate | 2016 |
| ASG Property Investments Limited | Real estate | 2023 |
| ASH Way EYE Services Limited | Health & social care | 2021 |
| ASH Way Investments Limited | Real estate | 2024 |
| Asha Retail Ltd | Wholesale & retail | 2025 |
| Ashes Developments Ltd | Construction | 2026 |
| Ashok Medical Ltd | Health & social care | 2018 |
| Ashris Global Limited | Financial services | 2025 |
| Ashton Air Compressors Ltd | Manufacturing | 2026 |
| Asian Foods Shop Ltd | Wholesale & retail | 2020 |
| Askiza Limited | Construction | 2026 |
| ASM Utility Services Ltd | Construction | 2023 |
| Asma & Soyon Co Ltd | Hospitality | 2024 |
| Aspen Tree Surgery Ltd | Administrative & support | 2013 |
| Aspire Square Ltd | Information & communication | 2019 |
| Assigned Healthcare Limited | Administrative & support | 2021 |
| Asteer Limited | Information & communication | 2016 |
| Astley Transport Limited | Transport & logistics | 2022 |
| Astra Threads and Trimmings Limited | Wholesale & retail | 1994 |
| Astraware Limited | Information & communication | 2000 |
| Astro Healthcare Limited | Health & social care | 2019 |
| Astute Orthopaedic Solutions Limited | Health & social care | 2015 |
| ATA Exchange Ltd | Other services | 2012 |
| ATC Holdings Group Limited | Financial services | 2026 |
| Atec Holdings Limited | Real estate | 2007 |
| Athena & Poseidon Wellness Limited | Arts & recreation | 2025 |
| Atkins Home Solutions Ltd | Financial services | 2025 |