| Adam’S Driving Academy Ltd | Education | 2025 |
| Adapt Vantech Trading Limited | Information & communication | 2024 |
| Adaptive Assessment Ltd | Education | 2025 |
| Adaptive Machine Patterns Limited | Professional & scientific | 2024 |
| Adaria Composites Ltd | Manufacturing | 2026 |
| Adastra Creative Ltd. | Information & communication | 2005 |
| Adastra Development Limited | Information & communication | 2013 |
| Adastra Test Equipment Hire Ltd | Manufacturing | 2026 |
| ADB70 Ltd | Manufacturing | 2025 |
| ADC Brown Ltd | Professional & scientific | 2020 |
| ADC Distributions Ltd | Wholesale & retail | 2026 |
| ADC Resourcing Ltd | Administrative & support | 2026 |
| Adcock Property Investments Ltd | Real estate | 2023 |
| Addenbrooke's Charitable Trust | Health & social care | 2016 |
| Adder Trustees Limited | Financial services | 2025 |
| Addomedia Limited | Information & communication | 2003 |
| Adea Global UK Ltd | Wholesale & retail | 2025 |
| Adeel & Berwin Estates Ltd | Real estate | 2025 |
| Adeelcare Ltd | Health & social care | 2025 |
| Ademnat Ltd | Construction | 2022 |
| Adeola Company Limited | Construction | 2018 |
| Adeptium Consulting Ltd | Information & communication | 2010 |
| ADF Asset Management (UK) Limited | Financial services | 2024 |
| ADF Asset Management LLP | | 2024 |
| ADG Commercial Estate Ltd | Real estate | 2022 |
| ADG Residential Estate Ltd | Real estate | 2022 |
| ADH Property London Limited | Real estate | 2016 |
| Adhara AI Ltd | Information & communication | 2025 |
| ADI AMA Ltd | Manufacturing | 2025 |
| ADI Hangu 1976 Ltd | Manufacturing | 2024 |
| ADI Motorsport Ltd | Manufacturing | 2026 |
| Adil Khan Investments Limited | Real estate | 2020 |
| Adilias Station Road Bakery Ltd | Manufacturing | 2016 |
| Adis Holdings Limited | Real estate | 2018 |
| Adisak Water Technology Co., Ltd | Water & waste | 2023 |
| Adishk DFT Consulting Ltd | Information & communication | 2026 |
| Adisonski Ltd | Manufacturing | 2026 |
| Adit Development UK Ltd | Mining & quarrying | 2022 |
| Adit Properties Limited | Real estate | 2019 |
| Adkwik Holdings Limited | Financial services | 2024 |
| Adkwik Limited | Wholesale & retail | 2018 |
| Admac Innovations Ltd | Professional & scientific | 2023 |
| Admirals Court (Freehold) Limited | Households | 2001 |
| Admirals Court (Reading) Limited | Households | 1988 |
| Admiralty Quarter (Portsmouth) Management Limited | Households | 2005 |
| Adonai's Promise Land Limited | Real estate | 2022 |
| Adop UK Ltd. | Real estate | 1994 |
| Adora Digital Health Ltd | Information & communication | 2020 |
| Adore.Life Limited | Health & social care | 2016 |
| ADR Ventures Limited | Administrative & support | 2026 |
| Adrenaline Martial Arts LLP | | 2013 |
| Adrenaline Proshop Ltd | Wholesale & retail | 2013 |
| Adrian Aviation Ltd | Manufacturing | 2025 |
| Adrian Bizdoaca Ltd | Manufacturing | 2026 |
| Adrian Paul Sawston Limited | Other services | 2016 |
| ADS Biotec Limited | Manufacturing | 1996 |
| ADS Construction Services Ltd | Construction | 2008 |
| ADS Resourcing Limited | Professional & scientific | 2020 |
| Adset Marketing Limited | Information & communication | 2025 |
| ADT Consultants Limited | Wholesale & retail | 2022 |
| Advance Holdings Group Limited | Professional & scientific | 2025 |
| Advanced CNC Solutions Ltd | Professional & scientific | 2025 |
| Advanced Fork Truck Training Limited | Education | 2010 |
| Advanced Furnace Technology Ltd. | Manufacturing | 1983 |
| Advanced Inkjet Solutions Ltd | Professional & scientific | 2023 |
| Advanced Insights Ltd | Information & communication | 2022 |
| Advanced Micro Devices (U.K.) Limited | Wholesale & retail | 1973 |
| Advanced Orthopaedic Measurement Limited | Health & social care | 2015 |
| Advanced Project Technology Limited | Professional & scientific | 1994 |
| Advanced Semitool Technology Ltd | Wholesale & retail | 2014 |
| Advancement Quest Limited | Professional & scientific | 2025 |
| Advanceregion Property Management Limited | Households | 1992 |
| Advand Ltd | Professional & scientific | 2015 |
| Advantage Media Limited | Information & communication | 1989 |
| Advent Bioservices Ltd | Manufacturing | 2013 |
| Adventiq Limited | Professional & scientific | 2005 |
| Adviisa Group Limited | Information & communication | 2025 |
| ADW Realty Ltd | Real estate | 2026 |
| Adwell Limited | Households | 1997 |
| ADY Karr Roth Ltd | Transport & logistics | 2021 |
| Adyan Khan Investments Limited | Real estate | 2020 |
| Ae&Ae Ltd | Financial services | 2015 |
| AEA Supply Ltd | Wholesale & retail | 2023 |
| Aecea Landscapes Limited | Administrative & support | 2013 |
| AED AED Ltd | Manufacturing | 2025 |
| Aegis Capital Partners Limited | Financial services | 2025 |
| Aegis Fleet Ltd | Transport & logistics | 2025 |
| Aegis Performance Products Limited | Manufacturing | 2026 |
| Aegis Trading Ltd | Wholesale & retail | 2025 |
| Aegisun Tech Ltd | Wholesale & retail | 2025 |
| AEH Neurosurgery Limited | Health & social care | 2022 |
| Aeiaedge Ltd | Wholesale & retail | 2025 |
| Aelora Limited | Professional & scientific | 2025 |
| Aelusive Ltd | Information & communication | 2023 |
| Aeola & Aubin Ltd | Health & social care | 2015 |
| Aequisym AI Limited | Information & communication | 2022 |
| Aequitas Properties Limited | Real estate | 2024 |
| Aerandil Technologies Ltd | Information & communication | 2026 |
| Aerial Collective Limited | Arts & recreation | 2022 |
| Aero Alex Ltd | Manufacturing | 2024 |