| ADC04 Ltd | Transport & logistics | 2021 |
| Adelphi Two Limited | Hospitality | 2025 |
| Adept Vehicle Management Limited | Extraterritorial | 2014 |
| Adept Vehicle Solutions Limited | Wholesale & retail | 2002 |
| ADF Mechanical Ltd | Construction | 2025 |
| ADF Plumbing and Heating Ltd | Extraterritorial | 2024 |
| ADG Services (Staffs) Ltd | Hospitality | 2024 |
| ADM Automotive Ltd | Wholesale & retail | 2017 |
| Admi Limited | Wholesale & retail | 2006 |
| Adscan Computing Limited | Information & communication | 1990 |
| ADV4NCE CIC | Education | 2026 |
| ADV4NCE Group Limited | Financial services | 2024 |
| ADV4NCE Sports Ltd | Education | 2026 |
| Advanced Bio-Extracts Limited | Professional & scientific | 2000 |
| Advanced Cardiac Surgery Ltd | Health & social care | 2016 |
| Advanced Enterprise Limited | Real estate | 2015 |
| Advantage Exam Preparation Limited | Education | 2016 |
| Advantech Europe B.V. | | 2023 |
| AER Quality Limited | Professional & scientific | 2011 |
| Aesthetica Medica Ltd | Health & social care | 2017 |
| Affinity Wealth Management (NW) Limited | Professional & scientific | 2009 |
| African Speciality Products Limited | Agriculture & fishing | 2000 |
| AFS Wealth Management Ltd | Financial services | 2004 |
| AG Education Focus Ltd | Education | 2016 |
| Against the Grain Bar Ltd | Hospitality | 2022 |
| AGD Transport Solution Limited | Transport & logistics | 2025 |
| AGF Foods Limited | Manufacturing | 2020 |
| Agile Education Limited | Education | 2024 |
| Agileops Consulting Ltd | Information & communication | 2025 |
| AGM Financial Limited | Professional & scientific | 2012 |
| Agmt Couriers Ltd | Transport & logistics | 2021 |
| Ahec Ltd | Agriculture & fishing | 2024 |
| Aheer Property Limited | Real estate | 2022 |
| AHM Multi-Activities Ltd | Construction | 2024 |
| AIB Mech Services Ltd | Professional & scientific | 2022 |
| AID and Empower Foundation | Health & social care | 2024 |
| AIM Electrical Engineer Limited | Construction | 2022 |
| AIM7 Ltd | Information & communication | 2019 |
| Aimss Suppliers Limited | Hospitality | 2023 |
| Airis Ventures Ltd | Wholesale & retail | 2024 |
| Airports R US Limited | Extraterritorial | 2023 |
| AJ & Sons Investments Limited | Real estate | 2014 |
| AJF Project Management Ltd | Professional & scientific | 2025 |
| AJH Brickwork Ltd | Construction | 2023 |
| AJN Properties(Newcastle) Limited | Real estate | 2025 |
| AJR Heating Services Ltd | Construction | 2025 |
| AJW Security Services Ltd | Administrative & support | 2016 |
| Ak&V Ltd | Health & social care | 2022 |
| Akall Ltd | Wholesale & retail | 2024 |
| Akenside (Brewery Bond) Limited | Construction | 2000 |
| Akinolam Global Logistics Limited | Wholesale & retail | 2026 |
| Akshaj Trading Ltd | Wholesale & retail | 2024 |
| Alabala Ltd | Wholesale & retail | 2019 |
| Alan Darby Carpentry Limited | Construction | 2002 |
| Alan Finney Antiques Limited | Wholesale & retail | 2004 |
| Alan Sofi Ltd | Other services | 2026 |
| Alan Wilde Engineering Ltd | Professional & scientific | 2019 |
| Albert Bear Limited | Health & social care | 2013 |
| Albion Business Communications Limited | Wholesale & retail | 2014 |
| Alcock & Bailey Limited | Construction | 1986 |
| Alessi Estates Limited | Real estate | 2017 |
| Alexii Ltd | Transport & logistics | 2014 |
| Alina Mihai Ltd | Health & social care | 2020 |
| Alishba Huda Ltd | Wholesale & retail | 2024 |
| ALL Aspects Roofing & Renovations Ltd | Construction | 2021 |
| ALL Counties Truck Movements Limited | Transport & logistics | 2023 |
| ALL Counties Vehicle Logistics Limited | Transport & logistics | 2012 |
| ALL Foods Engineering (Staffs) Limited | Manufacturing | 2006 |
| ALL Metal Fabrication & Finishing Ltd | Manufacturing | 2006 |
| ALL People Active CIC | Health & social care | 2018 |
| ALL Seasons Roofing & Scaffolding Limited | Construction | 1997 |
| Allendale Care Holdings Limited | Financial services | 2022 |
| Allens Autos Ltd | Wholesale & retail | 2024 |
| Alliance & West Ltd. | | 2000 |
| Allmark Estate Management Ltd | Real estate | 2026 |
| Alluvia Limited | Other services | 2025 |
| Alnmouth Escapes Limited | Hospitality | 2015 |
| Aloos Limited | Professional & scientific | 2018 |
| Alpha 11 11 Ltd | Households | 2025 |
| Alpha Competitions Ltd | Wholesale & retail | 2025 |
| Alpha Double G Afro Carribbean Store Ltd | Wholesale & retail | 2026 |
| Alpha HPF Ltd | Arts & recreation | 2019 |
| Alpha Revive Ltd | Health & social care | 2023 |
| Alsager Printing Company Limited | Manufacturing | 1979 |
| Alsager Roofing Co. Limited | Wholesale & retail | 1976 |
| ALT DEV Ltd | Information & communication | 2020 |
| ALT Three Services Limited | Information & communication | 2015 |
| Altaris Executive Limited | Administrative & support | 2025 |
| Altnadue Mechanical Services Ltd | Construction | 2026 |
| AMA Commercial Interiors Ltd | Professional & scientific | 2026 |
| AMB Healthcare Recruitment Ltd | Administrative & support | 2017 |
| Ambridge Thermoplastics Limited | Extraterritorial | 2014 |
| Ambrose Holiday Lets Ltd | Hospitality | 2025 |
| AMC Secure Solutions Ltd | Other services | 2024 |
| Amck Draughting Consultancy Limited | Professional & scientific | 2007 |
| AMD Joinery and Building Limited | Construction | 2017 |
| Amdora Homes Limited | Construction | 2026 |
| AMG Pipework Services Ltd | Construction | 2013 |
| Amka Limited | Transport & logistics | 2017 |
| Amorcare Mobility Stores Limited | Wholesale & retail | 2009 |