| ADS Workservcs PC | | 2020 |
| ADS Youtube Promotion LLP | | 2022 |
| Adsexpert Limited | Information & communication | 2024 |
| Adsfly Ltd | Professional & scientific | 2025 |
| Adslytic Limited | Administrative & support | 2019 |
| Adsmod Limited | Wholesale & retail | 2011 |
| Adsum (U.K) Limited | Professional & scientific | 2006 |
| Adsun Group Ltd | Administrative & support | 2016 |
| Adsworld Solutions Ltd | Information & communication | 2025 |
| Adswrq Mart Ltd | Wholesale & retail | 2025 |
| ADT Chiropractic Ltd | Health & social care | 2017 |
| Adtizer Limited | Information & communication | 2020 |
| ADV Holdings Ltd | Financial services | 2024 |
| Advance Agencies Ltd | Manufacturing | 2014 |
| Advance Air Limited | Manufacturing | 1998 |
| Advance Communications UK Limited | Information & communication | 2007 |
| Advance Construction Personnel Ltd | Professional & scientific | 2020 |
| Advance Home Solutions Ltd | Administrative & support | 2021 |
| Advance HR Solutions Limited | Administrative & support | 2025 |
| Advance Hydro, Ltd | Professional & scientific | 2023 |
| Advance Payroll and Tax Limited | Professional & scientific | 2017 |
| Advance Sectional Buildings Limited | Wholesale & retail | 1967 |
| Advance Training Academy (UK) Ltd. | Other services | 2009 |
| Advance Training and Consultancy Ltd | Education | 2021 |
| Advanced Access Limited | Administrative & support | 1994 |
| Advanced Biotherapies Limited | Professional & scientific | 2010 |
| Advanced Business Innovation Limited | Information & communication | 2020 |
| Advanced Business Solutions Ltd | Construction | 2017 |
| Advanced Ceiling Systems Limited | Wholesale & retail | 1967 |
| Advanced Cleaning Systems Limited | Manufacturing | 2013 |
| Advanced Computer Software Solutions Ltd | Information & communication | 2025 |
| Advanced Digital Engineering Ltd | Information & communication | 2022 |
| Advanced Electrical & Fire Ltd | Construction | 2024 |
| Advanced External Cleaning Limited | Administrative & support | 2024 |
| Advanced Global Group Limited | Administrative & support | 2016 |
| Advanced Hydration Technology Ltd | Professional & scientific | 2016 |
| Advanced Integrated Clinic Ltd | Health & social care | 2025 |
| Advanced Invasives Ltd | Construction | 2016 |
| Advanced Link Strategies Ltd | Information & communication | 2025 |
| Advanced Luxury Properties Ltd | Real estate | 2024 |
| Advanced M&E Solutions Limited | Information & communication | 2017 |
| Advanced Medical Simulation Online Limited | Professional & scientific | 2015 |
| Advanced Refurbishments Ltd | Construction | 2018 |
| Advanced Satellite Solutions Limited | Administrative & support | 2005 |
| Advanced Secure Technologies Holdings Ltd | Professional & scientific | 2006 |
| Advanced Secure Technologies Ltd | Administrative & support | 1995 |
| Advanced Sustainable Developments Limited | Manufacturing | 2016 |
| Advanced Tech Business Limited | Professional & scientific | 2024 |
| Advanced Total Fire Protection Ltd | Manufacturing | 2022 |
| Advanced Traffic Control Ltd | Real estate | 2015 |
| ADVANCEFIRE24 Ltd | Financial services | 2020 |
| Advantage Accountancy & Advisory (Cardiff) LLP | | 2010 |
| Advantage Accountancy & Advisory Ltd | Professional & scientific | 2017 |
| Advantage Assets Ltd | Real estate | 2024 |
| Advantage Contracts & Agency Ltd | Administrative & support | 2020 |
| Advantage Digital Marketing Ltd | Professional & scientific | 2022 |
| Advantage Holding Company Ltd | Financial services | 2014 |
| Advantage Spring Ltd | Education | 2013 |
| Advantine Limited | Administrative & support | 2014 |
| Advanto Trading and Investments Limited | Wholesale & retail | 2020 |
| Advatech Air Ambulance Services Limited | Transport & logistics | 2017 |
| Advatech Healthcare Europe Limited | Transport & logistics | 2012 |
| Advent Trade Ltd | Construction | 2016 |
| Adventure Residentials Ltd | Administrative & support | 2019 |
| Adventurekit Limited | Wholesale & retail | 2002 |
| Adventurers Quay Management Company Limited | Households | 1997 |
| Adventuring Limited | Wholesale & retail | 2022 |
| Adventus Nominees Limited | Financial services | 2024 |
| Advert Mentor Limited | Administrative & support | 2022 |
| Advertere Limited | Professional & scientific | 2019 |
| Advertising Fortress Limited | Information & communication | 2022 |
| Advertising Solutions Limited | Professional & scientific | 2019 |
| Advertx Media Ltd | Professional & scientific | 2024 |
| Advidan Limited | Information & communication | 2024 |
| Advik Republic Ltd | Wholesale & retail | 2024 |
| Advising Solutions Limited | Health & social care | 2026 |
| Advision Strategies Ltd | Information & communication | 2025 |
| Advitalis Ltd | Health & social care | 2025 |
| ADVOCA8 UK Limited | Administrative & support | 2017 |
| Advocacy & Capacity Development Association Ltd | Professional & scientific | 2023 |
| Advocacy Matters (Wales) | Health & social care | 1996 |
| Advocacy Support in Cymru Ltd | Health & social care | 2011 |
| Advocating Action Ltd | Professional & scientific | 2016 |
| ADW Consultancy Services Limited | Information & communication | 2011 |
| ADW Education Ltd | Education | 2024 |
| Adwaa Almarai for Engineering Consulting Ltd | Professional & scientific | 2025 |
| Adwise Advertising Limited | Information & communication | 2025 |
| Adzappy Ltd | Professional & scientific | 2018 |
| Adzenvisuals Ltd | Information & communication | 2025 |
| AE Academy Ltd | Information & communication | 2025 |
| AE Arma-Elektropanc Building Services Limited | Construction | 2015 |
| AE Promo Events Ltd | Hospitality | 2019 |
| AE1 Lettings Limited | Real estate | 2019 |
| Aearnmoney Co., Ltd | Wholesale & retail | 2021 |
| Aeboncology Ltd | Health & social care | 2012 |
| AEG Builders Ltd | Manufacturing | 2018 |
| Aegea Limited | Wholesale & retail | 2020 |
| Aegean Transport & Logistics Ltd | Transport & logistics | 2018 |
| Aegis Cleaning Ltd | Administrative & support | 2025 |
| Aegis Conglomerate Limited | Administrative & support | 2001 |