| Adams CUT Ltd | Other services | 2022 |
| Adams Homes & Property Ltd | Hospitality | 2026 |
| Adams Local Ltd | Wholesale & retail | 2025 |
| Adams Thornton Ltd | Health & social care | 2023 |
| Adamsons Vehicle Centre Limited | Administrative & support | 2015 |
| Adamsons Wimpole Limited | Wholesale & retail | 1998 |
| Adan Technologies Limited | Information & communication | 2012 |
| Adapt Residential Properties Ltd | Real estate | 2023 |
| Adapt Studios Limited | Other services | 2012 |
| ADB Contracts Ltd | Manufacturing | 2011 |
| ADB Finance Ltd | Financial services | 2016 |
| ADB Property Ltd | Real estate | 2016 |
| ADB S & S Ltd | Construction | 2020 |
| ADC Silver Star Properties Ltd | Real estate | 2023 |
| Adco N/W Limited | Administrative & support | 2009 |
| Adcock Occupational Health Services Ltd | Health & social care | 2020 |
| ADD Groundworks and Construction Ltd | Construction | 2023 |
| ADD to Basket Limited | Wholesale & retail | 2026 |
| Addy's Italian Ltd | Hospitality | 2026 |
| ADE OMO ADE Limited | Wholesale & retail | 2022 |
| ADE Plumbing & Heating Limited | Construction | 2005 |
| Adena Accountancy Ltd | Professional & scientific | 2025 |
| Adept ALL in One Ltd | Administrative & support | 2019 |
| Adept Taxation Services Limited | Professional & scientific | 2026 |
| Adhd Vibes Limited | Wholesale & retail | 2025 |
| ADI Boutique UK Limited | Wholesale & retail | 2026 |
| ADI UK Holding Limited | Construction | 2025 |
| Adi-Gardiner Limited | Wholesale & retail | 1977 |
| Adjanet Limited | Information & communication | 2025 |
| Adlitam Limited | Construction | 2018 |
| Adluni Company Ltd. | Construction | 2017 |
| ADM Oldham Ltd | Transport & logistics | 2016 |
| Admino Ltd | Administrative & support | 2025 |
| Adnan Adif Ltd | Transport & logistics | 2022 |
| Adnan Masood Limited | Financial services | 2014 |
| ADO Interactive Ltd | Professional & scientific | 2025 |
| Adpulse Ecom Ltd | Wholesale & retail | 2024 |
| Adrian Ispas Ltd | Wholesale & retail | 2019 |
| ADT Transport Ltd | Transport & logistics | 2023 |
| Adtel Limited | Information & communication | 2005 |
| Adun Haven Limited | Wholesale & retail | 2025 |
| Adupresh Resources Ltd | Information & communication | 2024 |
| Advance Fitness Solutions Limited | Other services | 2011 |
| Advance Pro Ltd | Real estate | 2023 |
| Advance Quality Glazing Ltd | Manufacturing | 2023 |
| Advance Quality Windows & Doors Limited | Manufacturing | 2020 |
| Advanced Airflow Solutions Limited | Administrative & support | 2006 |
| Advanced Detection Systems Limited | Administrative & support | 2003 |
| Advanced Installation Projects Ltd | Construction | 2021 |
| Advanced Lifts Ltd | Construction | 2018 |
| Advanced Metallurgical Services Limited | Professional & scientific | 1990 |
| Advanced Physio and Sports Injury Ltd | Health & social care | 2025 |
| Advanced Practitioner Clinical Services Ltd | Health & social care | 2016 |
| Advanced Supported Accommodation Ltd | Health & social care | 2025 |
| Advanceengines Ltd | Wholesale & retail | 2025 |
| Advider Limited | Manufacturing | 2014 |
| Adyan Restaurant Ltd | Hospitality | 2026 |
| AE Wharfe Ltd | Information & communication | 2023 |
| AEA Electrical Engineering Ltd | Construction | 2025 |
| Aeer Rita Care Ltd | Health & social care | 2018 |
| AEG Bars Limited | Hospitality | 2026 |
| AEG Lifting Ltd | Construction | 2025 |
| Aegis Design Limited | Professional & scientific | 2009 |
| Aelysia.Io Ltd | Information & communication | 2023 |
| AER Restaurants Limited | Hospitality | 2013 |
| Aerial Fitness Ltd | Arts & recreation | 2024 |
| Aerithiq AI Limited | Wholesale & retail | 2025 |
| Aero Global Ltd | Wholesale & retail | 2025 |
| Aero-Equip Ltd | Administrative & support | 2018 |
| Aerona (Air&Sea) Customs Clearing Agents Limited | Transport & logistics | 2006 |
| Aerovibes Limited | Wholesale & retail | 2026 |
| Aesthetic AG Ltd | Health & social care | 2020 |
| Aesthetics Deluxe Ltd | Other services | 2022 |
| Aetna Silk Screen Products, Inc. Limited | Information & communication | 2018 |
| Aews Ltd | Health & social care | 2024 |
| AF Boxing Ltd | Arts & recreation | 2020 |
| AF Driving School Ltd. | Administrative & support | 2025 |
| AF Electrics NW Ltd | Construction | 2023 |
| AF7860 Ltd | Professional & scientific | 2022 |
| AFB Electrical Ltd | Construction | 2023 |
| Afem Leasing and Trade Finance Brokers Limited | Professional & scientific | 2007 |
| Affilianta AI Limited | Wholesale & retail | 2025 |
| Affiliatrix AI Limited | Wholesale & retail | 2025 |
| Affilintel Limited | Wholesale & retail | 2025 |
| Affinity Care Services Ltd | Health & social care | 2026 |
| Affinity Childrens Home Ltd | Public administration | 2023 |
| Afghan Kebab House Restaurant Limited | Hospitality | 2026 |
| Afiah Wellbeing C.I.C. | Health & social care | 2025 |
| Afiniti Apparel Ltd | Wholesale & retail | 2026 |
| AFM Property Services Ltd | Real estate | 2021 |
| Afmh Rentals LLP | | 2025 |
| AFN Engineering Ltd | Professional & scientific | 2025 |
| AFR Estates Ltd | Real estate | 2021 |
| Afreuroames Services Global Ltd | Health & social care | 2025 |
| African Community Togetherness (ACT) Ltd | Other services | 2017 |
| African Culture Network (ACN) CIC | Education | 2025 |
| AFS Engineering Ltd | Professional & scientific | 2024 |
| Afsha Pharms Ltd | Health & social care | 2023 |
| Afshar Ahmad Transport Ltd | Transport & logistics | 2023 |
| After Breast Cancer Diagnosis C.I.C. | Other services | 2018 |