| Adeptus Projects Ltd | Professional & scientific | 2006 |
| Adeshield Limited | Financial services | 2025 |
| ADF Services Limited | Professional & scientific | 2019 |
| ADG Building and Joinery Ltd | Construction | 2025 |
| Adhartas Consulting Limited | Professional & scientific | 2021 |
| Adhd and ME CIC | Education | 2023 |
| Adhikari Consulting Limited | Professional & scientific | 2023 |
| Adioma Consulting Limited | Professional & scientific | 2021 |
| Adioma Realty Ltd | Real estate | 2024 |
| Aditya Group Global Ltd | Hospitality | 2025 |
| ADJ Facilities Limited | Transport & logistics | 2012 |
| ADJ Fire and Security Limited | Administrative & support | 2014 |
| Adjube Limited | Education | 2017 |
| ADL Autocare Ltd | Wholesale & retail | 2022 |
| ADM Civil Engineering Ltd | Construction | 2020 |
| ADM IFS Ltd | Professional & scientific | 2025 |
| ADM Mechanical Engineering Limited | Professional & scientific | 2018 |
| ADM Technical Solutions Limited | Administrative & support | 2011 |
| Admainplay Limited | Manufacturing | 2019 |
| Admantra Limited | Administrative & support | 2023 |
| Admeliora Art & Design Limited | Administrative & support | 2014 |
| Adms Control Systems Ltd | Information & communication | 2023 |
| Adonise Interiors Ltd | Professional & scientific | 2020 |
| Adosa Limited | Professional & scientific | 2017 |
| Adoyx-Uk Limited | Administrative & support | 2025 |
| ADR Developments Limited | Real estate | 2003 |
| ADR Property Investments Limited | Real estate | 2019 |
| ADR Residential Properties Limited | Real estate | 2022 |
| ADR Watches Limited | Professional & scientific | 2015 |
| Adrd Holdings Limited | Financial services | 2018 |
| Adrd Investments Limited | Professional & scientific | 2018 |
| Adrian Gallimore Ltd | Other services | 2019 |
| Adrian Gemenel Ltd | Transport & logistics | 2018 |
| Adrian Wallbank Legal Services Limited | Professional & scientific | 2021 |
| Adrians Couriers 24 Ltd | Transport & logistics | 2020 |
| Adscensio Limited | Professional & scientific | 2020 |
| Adseal Products Limited | Manufacturing | 2024 |
| Adsr Technologies Limited | Administrative & support | 2011 |
| Advance Finance & Leasing Ltd | Financial services | 2011 |
| Advance Fuels Limited | Extraterritorial | 1991 |
| Advance Hire Ltd | Administrative & support | 2017 |
| Advanced Bionics UK Limited | Other services | 1996 |
| Advanced Fibre Networks Ltd | Construction | 2022 |
| Advanced Fire Stopping Ltd | Construction | 2022 |
| Advanced Groundwork Supplies Limited | Construction | 1988 |
| Advanced Logistics Ltd | Transport & logistics | 2018 |
| Advanced NDT Inspection Solutions Ltd | Professional & scientific | 2021 |
| Advanced Skin Remedies Limited | Health & social care | 2023 |
| Advanced Skin Services Ltd | Health & social care | 2025 |
| Advanta Seeds Holdings UK Ltd | Agriculture & fishing | 2021 |
| Advantage Apparel Ltd | Wholesale & retail | 2025 |
| Adventure Mini Golf Ltd | Arts & recreation | 2007 |
| Adventures Down Memory Lane Limited | Information & communication | 2019 |
| Advisory Board for the Arts Limited | Professional & scientific | 2022 |
| Advisory Solutions Ltd | Professional & scientific | 2024 |
| Advisr Limited | Information & communication | 2026 |
| Advocatus Financial Limited | Administrative & support | 2013 |
| Advr Limited | Administrative & support | 2024 |
| AE Industrial & Air Equipment Limited | Wholesale & retail | 1977 |
| AEB Precision Limited | Manufacturing | 2009 |
| Aecare Ltd | Professional & scientific | 2022 |
| Aecotim Design Limited | Administrative & support | 2023 |
| AED Plumbing & Heating Ltd | Construction | 2026 |
| AEI Architecture Ltd | Professional & scientific | 2022 |
| AEL Consultants Limited | Construction | 2013 |
| AEL Estimating Limited | Administrative & support | 2011 |
| AEM Logisticks Ltd | Transport & logistics | 2021 |
| Aemh Vintners Limited | Other services | 2021 |
| Aenc Transport Ltd | Transport & logistics | 2016 |
| Aeolus Engineering Ltd | Administrative & support | 2025 |
| Aero Aviation Ltd | Administrative & support | 2025 |
| Aero Billionaire Limited | Manufacturing | 2022 |
| Aerocare Group (Warrington) Limited | Financial services | 2012 |
| Aeroco Aircraft Engineering Limited | Manufacturing | 2012 |
| Aerotech South West Ltd | Manufacturing | 2014 |
| Aesthetic Doctor Clinics Ltd | Health & social care | 2020 |
| Aesthetic Technology Ltd | Manufacturing | 2012 |
| Aesthetics Beauty LAB Ltd | Other services | 2023 |
| Aesthetics by EJM Limited | Other services | 2020 |
| Aesthetics One - Smp-Ink Ltd | Education | 2025 |
| Aether Law Limited | Professional & scientific | 2026 |
| Aetos Consulting Group Limited | Professional & scientific | 2021 |
| AF & L Ltd | Financial services | 2018 |
| AF Draughting Ltd | Professional & scientific | 2021 |
| AF Eco Limited | Water & waste | 2010 |
| AF Joinery Ltd | Construction | 2023 |
| AF Site Services Limited | Public administration | 2014 |
| Afdline Ltd | Information & communication | 2015 |
| Affinite Ltd | Administrative & support | 2023 |
| AFFINITY7 Consulting Ltd | Administrative & support | 2021 |
| Afflex Services Ltd | Other services | 2019 |
| Afixtech Ltd | Manufacturing | 2025 |
| Afjm Construction Limited | Administrative & support | 2008 |
| AFK Enterprise Limited | Health & social care | 2024 |
| Aflo Limited | Construction | 2023 |
| Afm-It Limited | Administrative & support | 2016 |
| Afry Solutions UK Limited | Professional & scientific | 1974 |
| After Blue Limited | Other services | 2011 |
| Afterprint Ltd | Manufacturing | 2019 |
| AG Contract Services Limited | Administrative & support | 2025 |