| Able Shutter Services Limited | Manufacturing | 2003 |
| Ablecrystalhomes Limited | Real estate | 2023 |
| Above & Beyond Tree Services Ltd | Agriculture & fishing | 2022 |
| ABR Building Services Ltd | Construction | 2021 |
| Abraham Homes Ltd | Real estate | 2024 |
| ABS Drainage Services Ltd | Construction | 2024 |
| Absolute Digital Media Limited | Information & communication | 2008 |
| Absolute Property and Rentals Ltd | Real estate | 2020 |
| Abundant Ownership Ltd | Real estate | 2022 |
| AC Renewable Systems Limited | Construction | 2021 |
| Accelerate Management Consultants Ltd | Administrative & support | 2013 |
| Access Facilities Management Limited | Administrative & support | 2020 |
| Accidents Body Repair Centre Ltd | Wholesale & retail | 2013 |
| Accountabilitylicensinggroup Ltd | Professional & scientific | 2026 |
| Ace Card Accounting Limited | Professional & scientific | 2025 |
| Ace Card Marketing Limited | Professional & scientific | 2026 |
| ACF Commercial Flooring Limited | Construction | 2025 |
| Acors Press Limited | Manufacturing | 1996 |
| ACR Advisory Ltd | Wholesale & retail | 2026 |
| ACT Roadways Limited | Real estate | 2014 |
| Actcare Limited | Construction | 2004 |
| Actef Ltd | Information & communication | 2022 |
| Action Marketing UK Ltd | Administrative & support | 2007 |
| ACTIV8 Fitness & Nutrition Ltd | Other services | 2023 |
| Actual Perceptions Ltd | Professional & scientific | 2021 |
| Actually, I CAN! Ltd | Education | 2021 |
| AD Flooring & Tiling Ltd | Construction | 2022 |
| Adam Lavis Ltd | Information & communication | 2021 |
| Adams Pipework Services Limited | Construction | 2009 |
| Adcock Agri Ltd | Administrative & support | 2013 |
| Addison Miller Ltd | Professional & scientific | 2018 |
| Adeola Odeku Ltd | Health & social care | 2022 |
| ADI Boardsports Limited | Wholesale & retail | 2011 |
| Adiyaman Elbistan 0246 Ltd | Hospitality | 2023 |
| Adlas Consulting Ltd | Information & communication | 2025 |
| ADT Analytics Limited | Professional & scientific | 2025 |
| Advance Glass Limited | Construction | 1997 |
| Advance Leadership and Coaching Limited | Professional & scientific | 2026 |
| Advanced Integrated Security Limited | Professional & scientific | 2009 |
| Advanced Mechanical Solutions Limited | Construction | 2015 |
| ADW Certifications Ltd | Households | 2021 |
| Aero-Chem Ltd | Professional & scientific | 2006 |
| Aesthetics Dunwell Limited | Other services | 2020 |
| Aethelred Property Limited | Real estate | 2017 |
| Affeng Limited | Professional & scientific | 2014 |
| Aforderble Catering Ltd | Hospitality | 2025 |
| AG Foods Essex Ltd | Hospitality | 2022 |
| Agent C Employment Limited | Administrative & support | 2020 |
| Agentchamp Ltd | Information & communication | 2026 |
| Agora Group Limited | Administrative & support | 2024 |
| Ahmed & Partners Limited | Other services | 2020 |
| Aiden Nest Limited | Real estate | 2024 |
| Aiken Spence Limited | Professional & scientific | 1999 |
| AIM Consultants Limited | Professional & scientific | 2012 |
| Aimd Investment Ltd | Financial services | 2025 |
| Aira Mahandru Limited | Hospitality | 2013 |
| Airflow Compliance Ltd | Administrative & support | 2025 |
| Airflow Containment Services Ltd | Energy | 2022 |
| Airtel Limited | Information & communication | 1985 |
| Aisp Ltd | Construction | 2015 |
| AJ Family Ltd | Construction | 2016 |
| AJ Sign Installations Limited | Administrative & support | 2014 |
| AJB Concrete Plant Hire Ltd | Administrative & support | 2026 |
| AJM Carpentry Design & Build Ltd | Construction | 2018 |
| AJP Property Investments Limited | Real estate | 2023 |
| AK Business Ltd | Construction | 2016 |
| AKP Professional Services Ltd | Health & social care | 2025 |
| Akropolis Restaurant Limited | Hospitality | 2013 |
| Aksel Consulting Ltd | Professional & scientific | 2024 |
| Aladdin Separation Technologies Ltd | Professional & scientific | 2020 |
| Alalava Investments Ltd | Financial services | 2018 |
| Alalava Management Limited | Transport & logistics | 2019 |
| Alan Hennessey Accountants and Tax Advisers Limited | Professional & scientific | 2017 |
| Alan Stanton & Co Ltd | Professional & scientific | 2010 |
| Albertjackbarbershop Limited | Other services | 2019 |
| Albion House Estates Ltd | Real estate | 2016 |
| Alchemy Leigh-On-Sea Ltd | Hospitality | 2020 |
| Aldborough Refurbishments Limited | Construction | 2013 |
| Alden Fire Consultants Limited | Professional & scientific | 2024 |
| Aldens Plumbing & Heating Ltd | Construction | 2024 |
| Aldson Building Contracts Ltd | Construction | 2023 |
| Alerta Ltd | Information & communication | 2013 |
| Alex Aesthetics Ltd | Health & social care | 2020 |
| Alex Joyce Consulting Limited | Information & communication | 2023 |
| Alexis Day Makeup & Hair Ltd | Other services | 2020 |
| ALI Zvezdata Limited | Other services | 2025 |
| Aline Real Estate Limited | Real estate | 2023 |
| Alisons Graphic Installations Limited | Other services | 2012 |
| ALK Plumbing & Drainage Limited | Construction | 2009 |
| ALL About Hands Limited | Health & social care | 2014 |
| ALL Building & Construction Ltd | Construction | 2024 |
| ALL Seasons Landscapes & Drives Limited | Construction | 2021 |
| ALL Steel Fabs Ltd | Manufacturing | 2022 |
| Allen & Hall Holdings Limited | Wholesale & retail | 1996 |
| Allen & Hall ME Ltd | Wholesale & retail | 2019 |
| Allheat & Plumbing Limited | Construction | 2022 |
| Allied Welding & Engineering Supplies Limited | Administrative & support | 2006 |
| Allington International Ltd | Real estate | 2026 |
| Allpile Foundations Limited | Construction | 1997 |
| Alltract Limited | Real estate | 2016 |