| Acquire Inc Limited | Professional & scientific | 2018 |
| Acquire Inc. Finance Limited | Information & communication | 2019 |
| Acre Aesthetics Holdings Limited | Wholesale & retail | 2026 |
| Acre Aesthetics Limited | Wholesale & retail | 2018 |
| ACT Fleet Solutions Ltd | Wholesale & retail | 2026 |
| Act&C Limited | Professional & scientific | 1997 |
| Actiflo Ltd | Wholesale & retail | 2026 |
| Actiitalk Limited | Information & communication | 2021 |
| Action Skip Hire Ltd | Other services | 2018 |
| Actium Properties Limited | Real estate | 2000 |
| Active Gym Ltd | Education | 2022 |
| Active Legal Limited | Professional & scientific | 2009 |
| Active Pursuits Limited | Administrative & support | 2019 |
| Active Swift Haul Logistics Ltd | Transport & logistics | 2026 |
| Actualcare Ltd | Administrative & support | 2012 |
| Acumen Tuition Limited | Education | 2018 |
| Acurelax Spa & Acupuncture Ltd | Other services | 2022 |
| Acuturn Limited | Professional & scientific | 2002 |
| AD HOC Digital Ltd | Professional & scientific | 2025 |
| AD Home Investments Ltd | Real estate | 2019 |
| Ad.Pharma Cover Limited | Wholesale & retail | 2025 |
| Adam & Muna Cakes Ltd | Manufacturing | 2025 |
| Adam Bartlett Property Developments Limited | Real estate | 2024 |
| Adam Bartlett Window Cleaning Ltd | Administrative & support | 2021 |
| Adam Convenience Ltd | Wholesale & retail | 2021 |
| Adam Ellis Saddles Limited | Extraterritorial | 2020 |
| Adam Motor Sales Limited | Wholesale & retail | 2020 |
| Adamant Scaffolding Limited | Construction | 2016 |
| Adams Enclosures Limited | Manufacturing | 2006 |
| Adams GAS and Electric Services Limited | Construction | 2025 |
| Adams Gascare Limited | Construction | 2017 |
| Adams Tours Limited | Transport & logistics | 2019 |
| Adams Transport and Logistics Service UK Ltd | Transport & logistics | 2026 |
| Adams Vehicle Logistics Ltd | Transport & logistics | 2026 |
| Adaptations Building Construction Limited | Construction | 2021 |
| Adaqua Limited | Agriculture & fishing | 2013 |
| Adbk Holdings Limited | Other services | 2018 |
| Adbrookes Ltd | Professional & scientific | 2025 |
| ADC Automotive Ltd | Wholesale & retail | 2024 |
| ADC Trading Limited | Other services | 2011 |
| Addax Holdings Limited | Financial services | 2022 |
| Addington Stores Limited | Wholesale & retail | 2000 |
| Addlite Limited | Manufacturing | 2016 |
| Addy and Family Ltd | Administrative & support | 2019 |
| Addy's Shawarma and Bunz Limited | Hospitality | 2025 |
| ADE Heritage Legacy Homes Ltd | Real estate | 2025 |
| ADEDAYO1 Healthcare Ltd | Health & social care | 2023 |
| Adel Builders Ltd | Construction | 2021 |
| Adelaide Engineering Company Limited | Manufacturing | 1960 |
| Adept Internal Audit Specialist Limited | Professional & scientific | 2026 |
| Adesso Compliance Limited | Administrative & support | 2012 |
| ADG Investments Limited | Real estate | 2022 |
| ADH Investments Limited | Real estate | 2020 |
| Adhesives Direct UK Limited | Manufacturing | 1994 |
| Adhkaar Real Estate Ltd | Real estate | 2025 |
| ADI Estate Management Ltd | Real estate | 2025 |
| ADI Fleet Services Ltd | Wholesale & retail | 2024 |
| Adinah Limited | Health & social care | 2022 |
| Adisos Ltd | Hospitality | 2024 |
| ADJ Commissioning Limited | Construction | 2014 |
| Adjs Composites Limited | Manufacturing | 2020 |
| Adlee Ltd | Hospitality | 2020 |
| ADM Legal Services Ltd | Other services | 2024 |
| Admiral Self Storage Ltd | Other services | 2000 |
| Adnan ET Younes Ltd | Manufacturing | 2025 |
| Adndr Ltd | Transport & logistics | 2025 |
| Adnic Holdings Limited | Financial services | 2025 |
| Adoctor Ltd | Health & social care | 2025 |
| Adom Electrical and Cleaning Services Ltd | Manufacturing | 2025 |
| Adoram Ltd | Extraterritorial | 2024 |
| Adore Designs Yorkshire Limited | Wholesale & retail | 2019 |
| Adore Serviced Apartments Ltd | Real estate | 2016 |
| Adornment by Adelle Ltd | Other services | 2026 |
| ADP Chiropractic Limited | Administrative & support | 2021 |
| ADR Decorators Limited | Construction | 2007 |
| Adrian S. Haulage Limited | Transport & logistics | 2015 |
| Adritrans Logistic Ltd | Transport & logistics | 2018 |
| Adroit Accessories Limited | Wholesale & retail | 1978 |
| ADS United Ltd | Wholesale & retail | 2018 |
| Adswift Digital Ltd | Wholesale & retail | 2024 |
| ADT Properties Ltd | Real estate | 2001 |
| Aduwaye Limited | Administrative & support | 2024 |
| Advance (UK) Enterprises Ltd | Wholesale & retail | 2009 |
| Advance Appliances Limited | Manufacturing | 2005 |
| Advance Heat Ltd | Construction | 2023 |
| Advance Heat Properties Ltd | Real estate | 2024 |
| Advance Leads Ltd | Wholesale & retail | 2020 |
| Advance Mobiles Limited | Wholesale & retail | 2022 |
| Advance Pharma Ltd | Wholesale & retail | 2011 |
| Advance Pharmacies Ltd | Health & social care | 1998 |
| Advance Upvc Ltd | Manufacturing | 2019 |
| Advanced Control Services Limited | Manufacturing | 2010 |
| Advanced Engineering Solutions Limited | Manufacturing | 1995 |
| Advanced Manufacturing Training Centre Ltd | Education | 2017 |
| Advanced Projects Westwood Group Limited | Construction | 2024 |
| Advanced Technicians Limited | Wholesale & retail | 2018 |
| Adventure Competitions Ltd | Wholesale & retail | 2024 |
| Adventureland Day Nursery Limited | Health & social care | 2009 |
| Adventureland Limited | Arts & recreation | 2005 |
| ADZ Clothing Limited | Wholesale & retail | 2020 |