| Abraham Solutions Limited | Other services | 2020 |
| Abrantie's Foundation Trust Community Interest Company | Health & social care | 2017 |
| Abrar Technical Supplies Ltd | Wholesale & retail | 2023 |
| Abri Health Care Ltd | Health & social care | 2025 |
| Absent Mind Clothing Ltd | Wholesale & retail | 2023 |
| Absolute Assured Security Limited | Administrative & support | 2010 |
| Absolute Dental Studios Limited | Health & social care | 2018 |
| Absolute Skincare Limited | Other services | 2010 |
| Abule Management Ltd | Real estate | 2025 |
| Abundis Homes Limited | Construction | 2025 |
| AC Student Travel Ltd | Administrative & support | 2011 |
| AC Accounting Support Ltd | Professional & scientific | 2018 |
| AC Chow Ltd | Hospitality | 2025 |
| Acada Academy Limited | Education | 2017 |
| Academy Recruitment Ltd | Administrative & support | 2013 |
| Acceptable Year Ltd | Health & social care | 2022 |
| Access and Mobility Bathrooms Ltd | Construction | 2022 |
| Access Building and Construction Ltd | Construction | 2025 |
| Accessacademy International Limited | Extraterritorial | 2011 |
| Accia Limited | Other services | 2024 |
| Accident Pro Services UK Ltd | Information & communication | 2025 |
| Accord Engineering Limited | Manufacturing | 2003 |
| Accounting Solutions for YOU Limited | Professional & scientific | 2019 |
| Accounts to Balance Ltd | Professional & scientific | 2010 |
| Accrete Care Services Ltd | Administrative & support | 2023 |
| Accrete Homes Ltd | Real estate | 2019 |
| Accuro Acbs Limited | Energy | 2006 |
| Ace Commercial Management Ltd | Administrative & support | 2011 |
| Ace Educational Consultants Limited | Education | 2019 |
| Ace Garage Doors Herts Limited | Construction | 2019 |
| Ace Healthcare Recruitment Ltd | Administrative & support | 2024 |
| Ace Hose Mobile Ltd | Professional & scientific | 2019 |
| Ace J Ltd | Health & social care | 2025 |
| Ace of Trees Ltd | Administrative & support | 2020 |
| Ace Taxis (Stevenage) Limited | Transport & logistics | 2000 |
| ACG (UK) Property Services Limited | Real estate | 2014 |
| ACG Property Ltd | Real estate | 2019 |
| Achieve Management Limited | Other services | 2012 |
| Achillea Property Investments Ltd | Real estate | 2023 |
| Acium Ltd | Manufacturing | 2015 |
| ACM Automotive Limited | Wholesale & retail | 2015 |
| Acorn PSH Ltd | Real estate | 2019 |
| Acorns to Oak Trees Mentoring Ltd | Education | 2025 |
| Acoustic Architecture UK Limited | Professional & scientific | 2009 |
| Acoustic Calibration Services Limited | Manufacturing | 2001 |
| Acre 1140 Limited | Construction | 2010 |
| Acrow Recruitment Ltd | Administrative & support | 2011 |
| ACS Aggregates Ltd | Wholesale & retail | 2019 |
| ACS Groundworks Ltd | Administrative & support | 2016 |
| Action Potential Venture Capital Limited | Professional & scientific | 2013 |
| Actionmanor Limited | Real estate | 2007 |
| Active Coach Limited | Other services | 2021 |
| Activer Ltd | Wholesale & retail | 2012 |
| AD Care Properties Limited | Real estate | 2019 |
| AD Properties India Limited | Other services | 2024 |
| AD Science Limited | Professional & scientific | 2020 |
| Adam Irving Limited | Construction | 2018 |
| Adam Klobukowski Ltd | Transport & logistics | 2015 |
| Adama Developments Ltd | Construction | 2025 |
| Adams-Electrical-Services Ltd | Construction | 2025 |
| Adan for YOU Ltd | Health & social care | 2019 |
| ADC Holdings Limited | Professional & scientific | 2016 |
| ADD Consultancy Services Limited | Information & communication | 2017 |
| Addai Entertainment Ltd | Information & communication | 2013 |
| Adele Avenue Residents Association Limited | Households | 1987 |
| Adem SB Ltd | Hospitality | 2021 |
| Ademayowa Global Limited | Administrative & support | 2024 |
| Aden Associates Limited | Construction | 1997 |
| ADF SET Construction Limited | Information & communication | 2015 |
| Adfina Limited | Information & communication | 2009 |
| ADI NO2 Management Limited | Other services | 2018 |
| Adklar Management Ltd | Real estate | 2025 |
| ADM Drainage Services Ltd | Water & waste | 2026 |
| Adom Professionals Limited | Health & social care | 2020 |
| ADP Art Ltd | Other services | 2019 |
| Adrian Koba Limited | Administrative & support | 2016 |
| Adrick Ltd | Real estate | 2026 |
| ADT Property Rentals Limited | Real estate | 2018 |
| Advance Digital Solutions Ltd | Information & communication | 2017 |
| Advanced Fluoropolymer Technology Limited | Professional & scientific | 2007 |
| Advanced Group PM Ltd | Construction | 2022 |
| Advanced Media Services Ltd | Administrative & support | 2009 |
| Adventure Village Limited | Other services | 2021 |
| Adverse Effect by Anietie Ekong Ltd | Arts & recreation | 2026 |
| Adviser Legal Limited | Professional & scientific | 2025 |
| Advotek Ltd | Extraterritorial | 2024 |
| Advs Technosolutions Limited | Information & communication | 2024 |
| Adxkom Limited | Extraterritorial | 2016 |
| Aegisgear Ltd | Wholesale & retail | 2025 |
| AEN Properties Limited | Real estate | 2022 |
| Aerofield Homes UK Ltd | Real estate | 2022 |
| Aeroflex Limited | Manufacturing | 1936 |
| Aerofloor Investments Limited | Administrative & support | 2012 |
| Aerospace Composites Limited | Information & communication | 2004 |
| Aerosurface Limited | Construction | 2018 |
| Aesthetic Mentor Group Ltd | Other services | 2024 |
| Aesthetics Life Ltd | Other services | 2019 |
| Aesthetics Painting & Decorating Ltd | Construction | 2023 |
| Aesthetics Perfected Ltd | Health & social care | 2020 |
| Aestrawave Ltd | Information & communication | 2025 |