| Adderstone 1993 Limited | Financial services | 2000 |
| Adderstone Civils Limited | Construction | 2024 |
| Adderstone Commercial Holdings Limited | Financial services | 2025 |
| Adderstone Construction (North East) Limited | Financial services | 2024 |
| Adderstone Construction Limited | Construction | 2023 |
| Adderstone Consulting Ltd. | Professional & scientific | 2000 |
| Adderstone Developments (110) Limited | Construction | 2019 |
| Adderstone Developments (111) Limited | Construction | 2019 |
| Adderstone Developments (113) Limited | Real estate | 2023 |
| Adderstone Developments (Stock) Limited | Construction | 2015 |
| Adderstone Facades Limited | Construction | 2025 |
| Adderstone Finance Limited | Financial services | 2019 |
| Adderstone Group Limited | Extraterritorial | 2018 |
| Adderstone Holdings Limited | Financial services | 2022 |
| Adderstone Limited | Extraterritorial | 2019 |
| Adderstone Living (UK) Limited | Financial services | 2023 |
| Adderstone Living Limited | Construction | 2020 |
| Adderstone Management Limited | Real estate | 2021 |
| Adderstone Projects Limited | Construction | 2005 |
| Adderstone Residential Holdings Limited | Transport & logistics | 2025 |
| Adderstone Steading Management Company Limited | Households | 2023 |
| Addictionne Ltd | Health & social care | 2025 |
| Addis Property Group Ltd | Construction | 2025 |
| Additive Intelligence Limited | Manufacturing | 2020 |
| Addo Education Limited | Education | 2023 |
| Adebayo Impact Studios Ltd | Information & communication | 2026 |
| Adebusola Adeyemi IT Services Ltd | Information & communication | 2023 |
| Adeegs Media Ltd | Information & communication | 2025 |
| Adein Country & Homes Limited | Real estate | 2023 |
| Adenin Digital Services Ltd | Information & communication | 2022 |
| Adept Building Consultancy Ltd | Professional & scientific | 2023 |
| Adept Modern Enterprises Ltd | Construction | 2024 |
| Adess Limited | Construction | 2024 |
| ADF Wind Ltd | Energy | 2021 |
| ADH Property Services Ltd | Households | 2015 |
| Adheen Limited | Wholesale & retail | 2024 |
| Adil Hussain Ltd | Health & social care | 2021 |
| Adin Convenience Store Ltd | Wholesale & retail | 2025 |
| Adina Reay Limited | Manufacturing | 2013 |
| ADJ Retail Ltd | Wholesale & retail | 2016 |
| Adjustopen Holdings Limited | Financial services | 2018 |
| Adjustopen Limited | Administrative & support | 1992 |
| ADL Builders (NE) Ltd | Construction | 2016 |
| Adlew 1963 Limited | Extraterritorial | 2014 |
| ADM Pressings (Holdings) Limited | Financial services | 2025 |
| ADM Pressings Limited | Manufacturing | 2008 |
| Admel Ltd | Manufacturing | 2025 |
| Admin N E Ltd | Administrative & support | 2015 |
| Admincareers Limited | Administrative & support | 2026 |
| Admirah Accountants Limited | Professional & scientific | 2025 |
| Admiral Chaloner Management Company Limited | Real estate | 2005 |
| Admiral Court (Bridlington) Management Company Limited | Households | 2003 |
| Adnaan Qureshi Medical Ltd | Information & communication | 2014 |
| Adobo Homes Limited | Real estate | 2024 |
| Adoc Moving Ltd | Transport & logistics | 2024 |
| Adonai Health Care Limited | Health & social care | 2016 |
| Adonai Property Holdings Ltd | Real estate | 2025 |
| Adoozle Stores Ltd | Wholesale & retail | 2026 |
| Adopted Digital Ltd | Professional & scientific | 2023 |
| Adov Estates and Properties Limited | Real estate | 2023 |
| ADP Precision Engineering Limited | Administrative & support | 2002 |
| ADP Precision Holdings Limited | Professional & scientific | 2010 |
| ADR Consultancy Ltd | Professional & scientific | 2011 |
| Adrana Limited | Extraterritorial | 2007 |
| Adrastea Limited | Professional & scientific | 2012 |
| Adressu Ltd | Other services | 2019 |
| Adrian's Courier Services Ltd | Transport & logistics | 2018 |
| Adriano Ltd | Wholesale & retail | 2011 |
| Adrize Ltd | Information & communication | 2022 |
| ADS E&I Limited | Construction | 2015 |
| Adtek Limited | Energy | 2012 |
| Adtek Prints Limited | Manufacturing | 2020 |
| Adunnis Closet Limited | Wholesale & retail | 2026 |
| ADVALU2U Ltd | Professional & scientific | 2020 |
| Advance Cleaning Applications Limited | Administrative & support | 2002 |
| Advance Finance NE Ltd | Administrative & support | 2022 |
| Advance Installations Limited | Construction | 2005 |
| Advance Mortgage Funding Limited | Financial services | 1988 |
| Advance Publishing Ltd | Information & communication | 2024 |
| Advanced Adhesives Ltd. | Professional & scientific | 1996 |
| Advanced Chiropody & Podiatry Ltd | Health & social care | 2025 |
| Advanced Compressor Solutions Limited | Manufacturing | 2015 |
| Advanced Digital Transformation Ltd | Information & communication | 1980 |
| Advanced Electronics Limited | Manufacturing | 1999 |
| Advanced Engineering Solutions (UK) Limited | Professional & scientific | 2010 |
| Advanced Healthcare Group Limited | Financial services | 2024 |
| Advanced Remote Solutions Ltd | Administrative & support | 2026 |
| Advanced Retail Group Ltd | Wholesale & retail | 2025 |
| Advanced Safety Group Ltd | Other services | 2020 |
| Advanced Training Centre Ltd | Administrative & support | 2024 |
| Advanced Utility Management Limited | Other services | 2022 |
| Advanced Verification Monitoring Holdings Limited | Financial services | 2026 |
| Advanced Verification Properties Solutions Ltd | Real estate | 2026 |
| Advanceplace Property Management Limited | Households | 1992 |
| Advantage Testing UK Limited | Education | 2013 |
| Advantis Property Ltd | Real estate | 2023 |
| Adventure Alliance Films Ltd | Information & communication | 2022 |
| Adventure Hires NE Ltd | Administrative & support | 2024 |
| Adventure in Learning Ltd | Education | 2023 |
| Advice Construction Ltd | Construction | 2025 |