| Addvantage Digital Solutions Ltd | Information & communication | 2009 |
| ADE Airsource Heat Pump Ltd | Construction | 2026 |
| ADE Group Holdings Ltd | Financial services | 2022 |
| Adeera Ltd | Wholesale & retail | 2020 |
| Adelaide Business Park Ltd | Real estate | 2025 |
| Adept Project Management Limited | Professional & scientific | 2018 |
| Adepta One Limited | Professional & scientific | 2025 |
| Ades Beauty Ltd | Other services | 2025 |
| Adetech Ltd | Professional & scientific | 2019 |
| ADF Sports Ltd | Professional & scientific | 2022 |
| Adfm Investments Limited | Real estate | 2024 |
| ADG Fashion Ltd | Manufacturing | 2019 |
| ADH Transport Services Ltd | Transport & logistics | 2026 |
| Adhd Pharma Ltd | Health & social care | 2025 |
| ADI Europe Limited | Administrative & support | 1999 |
| ADI UK Limited | Administrative & support | 1997 |
| Adicom Ltd | Wholesale & retail | 2019 |
| Adil Distribution Limited | Transport & logistics | 2025 |
| Adil Electronics Ltd | Wholesale & retail | 2021 |
| Adil Fusions Ltd | Hospitality | 2024 |
| Adino Studios Limited | Information & communication | 2026 |
| ADK Holdings Limited | Financial services | 2015 |
| ADK Law Limited | Professional & scientific | 2015 |
| ADK Management Limited | Wholesale & retail | 2010 |
| ADK Property Holdings Limited | Real estate | 2022 |
| ADK Security Limited | Wholesale & retail | 1991 |
| Adkiero Ltd | Information & communication | 2021 |
| ADL & Dean Investments Ltd | Wholesale & retail | 2024 |
| ADL Fruit and VEG Ltd | Wholesale & retail | 2021 |
| Adlington Healthcare Limited | Wholesale & retail | 2024 |
| Adlington Valeting Chorley Road Ltd | Administrative & support | 2024 |
| ADM Procurement Consultancy Limited | Administrative & support | 2012 |
| ADM Travel Ltd | Transport & logistics | 2023 |
| Adman's Health Care Ltd | Health & social care | 2015 |
| Admark Creative Ltd | Manufacturing | 2025 |
| Admecom Limited | Wholesale & retail | 2025 |
| Administrative Assist Bolton Ltd | Administrative & support | 2016 |
| Administratum Ltd | Financial services | 2024 |
| Admiral Building Contracting (ABC) Ltd | Construction | 2026 |
| Admiral Lettings Limited | Real estate | 2020 |
| Admiral Property Developments Limited | Construction | 2020 |
| Admr Ltd | Wholesale & retail | 2022 |
| Adnan Ahmed Limited | Wholesale & retail | 2025 |
| Adocg Limited | Construction | 2026 |
| Adol - Transport Ltd | Transport & logistics | 2025 |
| Adonai's Haven Limited | Health & social care | 2025 |
| Adonia Aesthetics North West Ltd | Health & social care | 2020 |
| Adoptcert Protection Limited | Professional & scientific | 2022 |
| Ador Solutions Ltd | Administrative & support | 2025 |
| Adore Properties Limited | Real estate | 2015 |
| ADP Property Rental Ltd | Real estate | 2021 |
| Adport Limited | Professional & scientific | 2018 |
| ADR Engineering Northwest Ltd | Professional & scientific | 2024 |
| ADR Mortgage Services Limited | Administrative & support | 2022 |
| ADR Northwest Limited | Hospitality | 2019 |
| ADR Plant Solutions Ltd | Manufacturing | 2021 |
| Adrian Codarin Ltd | Transport & logistics | 2017 |
| Adrimun Restaurant and Cafe Ltd | Hospitality | 2025 |
| Adrimun Salon Limited | Other services | 2025 |
| ADS Construction Solutions Ltd | Construction | 2026 |
| ADS Pharms Ltd | Health & social care | 2015 |
| Advance Foster Care Limited | Extraterritorial | 2002 |
| Advance Pest Prevention Ltd | Other services | 2024 |
| Advance Satellite Services Limited | Construction | 2004 |
| Advanced Compliance Solutions Ltd | Professional & scientific | 2017 |
| Advanced Data Services Ltd | Information & communication | 2023 |
| Advanced Decision Modelling Ltd | Information & communication | 2017 |
| Advanced Deep Clean Limited | Other services | 2013 |
| Advanced Domestic Services Limited | Wholesale & retail | 2003 |
| Advanced Extensions Ltd | Construction | 2023 |
| Advanced Heritage Roofing Limited | Construction | 2015 |
| Advanced Internet Solutions Ltd. | Information & communication | 2000 |
| Advanced Pipeline Rehabilitation and Training Limited | Professional & scientific | 1994 |
| Advanced Pipeline Rehabilitation Technologies Ltd. | Manufacturing | 2002 |
| Advanced Reconstructive Solutions Limited | Extraterritorial | 2016 |
| Advanced Timber Frame Limited | Manufacturing | 2008 |
| Advant Limited | Wholesale & retail | 2022 |
| Advantage ADS Ltd | Information & communication | 2025 |
| Advent DS Limited | Construction | 2017 |
| Adventure 21 UK Ltd | Arts & recreation | 2024 |
| Adventure Clothing Limited | Manufacturing | 2021 |
| Adventure Garden Limited | Health & social care | 2025 |
| Advibe Marketing Limited | Professional & scientific | 2025 |
| Advice Factory Limited | Information & communication | 2005 |
| Advocare Limited | Health & social care | 2016 |
| Advocate Resources Ltd | Wholesale & retail | 2017 |
| Adyg Ltd | Transport & logistics | 2020 |
| Adyz Driving School Limited | Education | 2026 |
| Adyzee Properties Ltd | Real estate | 2025 |
| ADZ Creative and Digital Ltd | Professional & scientific | 2007 |
| ADZ Food Distribution Limited | Wholesale & retail | 2004 |
| Adzgroup Ltd | Hospitality | 2005 |
| AE Bathrooms and Kitchens Fitters Ltd | Construction | 2019 |
| AE Cosmetica Ltd | Wholesale & retail | 2025 |
| AEA Solutions Ltd | Information & communication | 2026 |
| Aeaglobal Ltd | Wholesale & retail | 2025 |
| Aecon Design Ltd | Administrative & support | 2025 |
| Aegis Regulatory Advisors Ltd | Professional & scientific | 2026 |
| AEH Innovative Hydrogel Ltd | Professional & scientific | 2018 |
| Aehd Limited | Administrative & support | 2016 |