| Active Progress Ltd | Education | 2019 |
| Active Recovery Therapy Ltd | Health & social care | 2017 |
| Active Regen Community Foundation Ltd | Education | 2010 |
| Active Steps Learning Ltd | Education | 2025 |
| Active Summer Camps Ltd | Health & social care | 2025 |
| Active Trucker Ltd | Transport & logistics | 2019 |
| Activfutures Support Ltd | Education | 2025 |
| Activities 4 Children (Sheffield) Limited | Arts & recreation | 2007 |
| Actus Health & Safety Ltd | Public administration | 2020 |
| Actus Risk Group Ltd | Financial services | 2023 |
| Actus Risk Management Services Ltd | Financial services | 2018 |
| Acuma Technology Limited | Administrative & support | 2012 |
| Acumen Safety Limited | Public administration | 2018 |
| Acuna Ents Limited | Administrative & support | 2025 |
| Acute Core Services Limited | Information & communication | 2026 |
| Acutispvt Limited | Wholesale & retail | 2025 |
| ACW Surfacing Limited | Construction | 2018 |
| AD Administration Limited | Administrative & support | 2024 |
| AD Art Limited | Other services | 2008 |
| AD Commodities Limited | Wholesale & retail | 2021 |
| AD Conglomerate Limited | Construction | 2024 |
| AD Dagger Limited | Wholesale & retail | 2023 |
| AD Education Ltd | Education | 2021 |
| AD Finance Group Limited | Financial services | 2024 |
| AD Future Houses Ltd | Real estate | 2020 |
| AD Joinery & Shopfitting Ltd | Construction | 2026 |
| AD Letting Services Ltd | Real estate | 2012 |
| AD Property Training Ltd | Education | 2021 |
| AD Quality Apartments Ltd | Real estate | 2020 |
| ADA & Co Accountancy Ltd | Professional & scientific | 2021 |
| ADA & Co Accounts Ltd | Professional & scientific | 2019 |
| ADA & Co Group Ltd | Financial services | 2021 |
| ADA & Co Legal Ltd | Administrative & support | 2022 |
| ADA Group Ltd | Financial services | 2023 |
| ADA Mortgages Ltd | Extraterritorial | 2024 |
| Ada's Trade Ltd | Transport & logistics | 2017 |
| Adabim Investment Company Ltd | Financial services | 2023 |
| Adagio Holden Ltd | Construction | 2014 |
| Adam Auto Sales Limited | Wholesale & retail | 2023 |
| Adam Bradley Business Growth Consultancy Ltd | Professional & scientific | 2024 |
| Adam Carr Chiropractic Limited | Health & social care | 2012 |
| Adam David Owens Wealth Management Limited | Administrative & support | 2017 |
| Adam Ellis Property Ltd | Real estate | 2022 |
| Adam Fabrications Ltd | Manufacturing | 2010 |
| Adam Griffiths Ltd | Hospitality | 2021 |
| Adam JAK Coaching Limited | Other services | 2026 |
| Adam Law Solicitors Limited | Professional & scientific | 2012 |
| Adam Mahmood Ltd | Public administration | 2022 |
| Adam Smith Stunts Ltd | Arts & recreation | 2019 |
| Adam Tailor Shop Ltd | Wholesale & retail | 2025 |
| Adam Vans & Cars Ltd | Wholesale & retail | 2026 |
| Adaman Limited | Transport & logistics | 2010 |
| ADAMGROUP21 Ltd | Wholesale & retail | 2020 |
| Adamoni Pata Limited | Hospitality | 2026 |
| Adams Driving Limited | Transport & logistics | 2018 |
| Adams House Medical Limited | Health & social care | 2013 |
| Adams Local Mini Market Ltd | Wholesale & retail | 2021 |
| Adams Used Cars for Sale Limited | Extraterritorial | 2022 |
| Adao Property Limited | Real estate | 2024 |
| Adapt Conversions Limited | Real estate | 2008 |
| Adapt Strength & Conditioning Limited | Education | 2024 |
| Adapt-Life Ltd | Professional & scientific | 2026 |
| Adaptation Asia Ltd | Professional & scientific | 2025 |
| Adas Centre Sheffield Ltd | Wholesale & retail | 2023 |
| ADB Joinery Limited | Construction | 2019 |
| ADB Property Rental Ltd | Real estate | 2024 |
| ADC Environmental Services Limited | Administrative & support | 2000 |
| Adcock Development Limited | Construction | 2016 |
| Addin Limited | Professional & scientific | 2008 |
| Addison Lloyd Limited | Real estate | 2023 |
| Addition Accountancy Limited | Professional & scientific | 2008 |
| Addition Limited | Administrative & support | 2009 |
| Additive Manufacturing Technologies Ltd | Information & communication | 2015 |
| Addocare Scole Limited | Health & social care | 2021 |
| Addparts Ltd | Manufacturing | 2024 |
| ADE Adesina & Co Limited | Professional & scientific | 2013 |
| Adec Investment Ltd | Health & social care | 2016 |
| Adee Engineering (Fabrications) Ltd | Manufacturing | 2003 |
| Adeem Transport Company 0102 Ltd | Transport & logistics | 2025 |
| Adefagbulu Limited | Hospitality | 2023 |
| Adegboyega Property Ltd | Real estate | 2026 |
| Adeireland Ltd | Professional & scientific | 2024 |
| Adekunle Odufuye Limited | Health & social care | 2025 |
| Adel Professional Limited | Wholesale & retail | 2007 |
| Adelaide Works Limited | Real estate | 2008 |
| Adelphi Creative CIC | Education | 2026 |
| Adem Property Development UK Limited | Construction | 2009 |
| Aden Corner Shop Limited | Wholesale & retail | 2026 |
| Adenohill Limited | Real estate | 2001 |
| Adept Electrical Contractors Ltd | Construction | 2010 |
| Aderans Building Ltd | Construction | 2025 |
| Aderans Invest Limited | Construction | 2018 |
| Adewick Ltd | Manufacturing | 2025 |
| Adfct Transport Ltd | Transport & logistics | 2025 |
| ADG Media Limited | Administrative & support | 2015 |
| Adharsh Medical Services Limited | Health & social care | 2015 |
| Adhd Care AI Ltd | Information & communication | 2025 |
| Adhdeasy Limited | Health & social care | 2023 |
| ADI Pro Leak Ltd | Professional & scientific | 2019 |
| Adil JEE Limited | Real estate | 2024 |