| Acteon Integrated Solutions Limited | Professional & scientific | 2016 |
| Acteon Middle East and FAR East Investments Limited | Administrative & support | 2007 |
| Acteon South American Investments Limited | Professional & scientific | 2006 |
| Acteon UK Financing Limited | Administrative & support | 2014 |
| Acteon West Africa Holding Limited | Financial services | 2020 |
| Actif Capital Ltd | Real estate | 2025 |
| Action Community Enterprises CIC | Administrative & support | 2011 |
| Action for Swifts Trading Ltd | Manufacturing | 2022 |
| Action Sports TV Limited | Information & communication | 2011 |
| ACTIONS4U Care Ltd | Health & social care | 2023 |
| ACTIV8 Gym Ltd | Arts & recreation | 2009 |
| Active Education Sports Coaching Limited | Education | 2023 |
| Active Group Holdings Limited | Financial services | 2026 |
| Active Help and Support Ltd | Health & social care | 2024 |
| Active Mortgage Solutions (East Anglia) Limited | Financial services | 2005 |
| Active Motion Injury Clinic (Eastleigh) Ltd | Health & social care | 2022 |
| Active Motion Injury Clinic (Port Solent) Ltd | Health & social care | 2022 |
| Active Servicing UK Limited | Administrative & support | 2013 |
| Active Workforce Solutions Ltd | Administrative & support | 2022 |
| Activity Holdings Ltd | Extraterritorial | 2023 |
| Acumen Logic Ltd | Education | 2024 |
| Acute Recruitment Consultants Limited | Health & social care | 2018 |
| ACY Property Management Limited | Real estate | 2022 |
| AD Aviation Service Limited | Professional & scientific | 2018 |
| AD Design & Construction Ltd | Construction | 2022 |
| AD Escape Enterprises Limited | Arts & recreation | 2019 |
| AD HOC Editorial Limited | Information & communication | 2013 |
| AD Holdings (Norfolk) Limited | Real estate | 2025 |
| AD Insolvency Limited | Information & communication | 2015 |
| ADA Homes Ltd | Construction | 2021 |
| ADA17 | Financial services | 2020 |
| Adam and Edith Ltd | Health & social care | 2024 |
| Adam Brock Plumbing & Heating Ltd | Construction | 2020 |
| Adam Cossey Ltd | Construction | 2023 |
| Adam From Home Ltd | Wholesale & retail | 2022 |
| Adam Grint Ltd | Other services | 2009 |
| Adam Guldemann Limited | Information & communication | 2016 |
| Adam Mills Developments Ltd | Construction | 2025 |
| Adam Power Associates Limited | Professional & scientific | 2009 |
| Adam Walters Limited | Wholesale & retail | 2010 |
| Adams & Howling (Holdings) Limited | Financial services | 2024 |
| Adams & Howling Limited | Agriculture & fishing | 1972 |
| Adams Property Developments Ltd | Construction | 2026 |
| Adams Roofing & Building Ltd | Construction | 2026 |
| Adamsarbor Ltd | Agriculture & fishing | 2025 |
| Adapt & Overcome Construction Limited | Construction | 2024 |
| Adapt Aviation Consulting Limited | Professional & scientific | 2013 |
| Adapt Events Ltd | Administrative & support | 2014 |
| Adaptar Axiom Ltd | Administrative & support | 2016 |
| Adaptar Solutions Limited | Financial services | 2003 |
| Adaptive Services Ltd | Wholesale & retail | 2015 |
| Adari Consulting Limited | Professional & scientific | 2022 |
| Adason Holdings Ltd | Real estate | 2026 |
| ADB Associates Limited | Financial services | 2025 |
| ADC Consulting Ltd | Information & communication | 2017 |
| Adcock Plant Ltd | Administrative & support | 2007 |
| ADD Distribution Ltd | Wholesale & retail | 2011 |
| Addeh Property Limited | Real estate | 2026 |
| Addicted Content Limited | Professional & scientific | 2013 |
| Addinall HR and Mediation Limited | Administrative & support | 2024 |
| Addison EAR Nose and Throat Clinic Ltd | Health & social care | 2026 |
| Additions Contractors Limited | Professional & scientific | 2014 |
| Adds Sparkle Limited | Professional & scientific | 1994 |
| Addwest Limited | Financial services | 2011 |
| Adecs (Norfolk) Limited | Information & communication | 2002 |
| Adelux Consulting Limited | Professional & scientific | 2014 |
| Adencross Limited | Real estate | 1988 |
| Adeolabayo Limited | Health & social care | 2021 |
| Adept Demand Limited | Administrative & support | 2022 |
| Adept Design (Norfolk) Ltd | Information & communication | 2003 |
| Adept EA Ltd | Construction | 2025 |
| Adept IT Solutions (Norwich) LLP | | 2022 |
| Adept Roofing & Property Solutions Ltd | Construction | 2026 |
| Adepta Limited | Professional & scientific | 2008 |
| Adeptcrest Limited | Professional & scientific | 1981 |
| Adetop Limited | Health & social care | 2022 |
| Adewole Limited | Professional & scientific | 2023 |
| ADG Praedium Ltd | Hospitality | 2006 |
| ADH Solutions Limited | Energy | 2021 |
| Adhd Coach Norfolk Ltd | Other services | 2025 |
| Adhd Pathways Ltd | Health & social care | 2025 |
| ADI DRY Liners Ltd | Construction | 2018 |
| Adiannah Limited | Financial services | 2018 |
| Adigun Property Limited | Real estate | 2026 |
| Adiy Ltd | Hospitality | 2026 |
| Admiral Building & Construction Limited | Administrative & support | 2008 |
| Admiral Commercial Cleaning Ltd | Administrative & support | 2016 |
| Admiral Trading (Norfolk) Limited | Hospitality | 2006 |
| Adms Asset Management Limited | Financial services | 2011 |
| ADN Consulting Ltd | Wholesale & retail | 2001 |
| Adnan's BNB Limited | Hospitality | 2019 |
| Adpoint Business Solutions Limited | Information & communication | 2016 |
| ADR Electrical Limited | Wholesale & retail | 2003 |
| Adraktas Consulting Ltd | Professional & scientific | 2023 |
| Adrian James Acoustics Limited | Professional & scientific | 2002 |
| Adrian Mortram Associates Limited | Professional & scientific | 1985 |
| Adrian Moya Ltd | Manufacturing | 2018 |
| Adrian Smith Accountants Limited | Professional & scientific | 2003 |
| Adrian Wade Consulting Services Limited | Professional & scientific | 2018 |
| ADS Gastro Limited | Health & social care | 2020 |