| Acorn 22 Holdings Limited | Hospitality | 2020 |
| Acorn Psychology Ltd | Education | 2010 |
| Acorns Care Ltd | Health & social care | 2025 |
| Acresfield Consultancy Limited | Information & communication | 2020 |
| Acrylic Canopy UK Ltd | Manufacturing | 2021 |
| ACS Direct Limited | Professional & scientific | 2019 |
| Action Against Cancer Limited | Health & social care | 2015 |
| Active Digital Solutions Limited | Information & communication | 2025 |
| Active EMS Ltd | Manufacturing | 2021 |
| Active EMS Owners Ltd | Financial services | 2022 |
| Active Physiotherapy Ltd | Health & social care | 2003 |
| Active Vehicle Solutions Ltd | Wholesale & retail | 2022 |
| Activinstinct Holdings Limited | Professional & scientific | 2013 |
| Activinstinct Ltd | Wholesale & retail | 2002 |
| Activity Works | Arts & recreation | 2014 |
| Actua Business Services Limited | Professional & scientific | 2001 |
| Acuity Coaching Limited | Professional & scientific | 2003 |
| AD Optics Ltd | Health & social care | 2018 |
| AD Property Holdings Limited | Real estate | 2022 |
| AD Property Investments Limited | Real estate | 2026 |
| AD Travel and Tourism Limited | Administrative & support | 2026 |
| AD Wetrooms Limited | Construction | 2025 |
| AD10 Events Ltd | Arts & recreation | 2025 |
| Adagio Solutions Limited | Professional & scientific | 2011 |
| Adam Cooper Communications Ltd | Information & communication | 2025 |
| Adam Fade Ltd | Other services | 2026 |
| Adams Autotec Limited | Wholesale & retail | 2012 |
| Adapt Building Services Ltd | Construction | 2012 |
| Adaptai Futures CIC | Education | 2025 |
| Adaptiviq Performance Engineering Ltd | Information & communication | 2025 |
| ADC Heat & Plumb Solutions Limited | Construction | 2024 |
| Adchieve Ltd | Wholesale & retail | 2025 |
| Adco Legal Limited | Professional & scientific | 2021 |
| ADD Technology Limited | Information & communication | 2003 |
| Adebayor UK Limited | Health & social care | 2019 |
| Adex Publishing Ltd | Information & communication | 2003 |
| ADG FIC Limited | Real estate | 2015 |
| Adhan Enterprises Ltd | Health & social care | 2021 |
| Adhesive Developments Limited | Manufacturing | 1967 |
| ADL Building Services & Fit-Out Limited | Construction | 2019 |
| Adminreview Ltd | Administrative & support | 2023 |
| Adnan’S Transport Limited | Transport & logistics | 2024 |
| ADS Electrical Solutions Ltd | Construction | 2025 |
| Adscreen Media Limited | Professional & scientific | 2020 |
| Advanced Build Group Ltd | Construction | 2019 |
| Advanced Building and Construction Ltd | Construction | 2020 |
| Advanced Dietics Limited | Administrative & support | 2009 |
| Advanced Environmental Solutions Ltd | Extraterritorial | 2020 |
| Advanced Intelligence Ltd | Administrative & support | 2021 |
| Advanced Traffic Ltd | Professional & scientific | 2020 |
| Advanced Utilities Limited | Construction | 2001 |
| Advancis Software & Services Ltd | Wholesale & retail | 2021 |
| Advantage Insurance Centres Limited | Financial services | 1995 |
| Advantex Ltd | Extraterritorial | 2019 |
| Adventure in Music CIC | Education | 2025 |
| Advocacy for Disabled People CIC | Information & communication | 2015 |
| Aeon Electrical Solutions LLP | | 2007 |
| Aero Innovations Ltd | Wholesale & retail | 2026 |
| AES Construction NW Limited | Construction | 2024 |
| Aesthetic Athletes Ltd | Health & social care | 2020 |
| AF Capital Ltd | Real estate | 2022 |
| Affinity Design Europe Limited | Real estate | 2017 |
| Affordable Housing Consultancy Limited | Professional & scientific | 2009 |
| Affordable Motor Cars (A6 MOT & Service Centre) Limited | Wholesale & retail | 2019 |
| Affordable Motor Cars Limited | Wholesale & retail | 2019 |
| Africa Al's Limited | Wholesale & retail | 2018 |
| Afterglow Tanning Studio Ltd | Other services | 2023 |
| Aftermath Autobodies Ltd | Wholesale & retail | 2022 |
| AG Auctions Ltd | Administrative & support | 2023 |
| AGE UK Bury | Health & social care | 2011 |
| AGE UK Bury Enterprises CIC | Health & social care | 2016 |
| Agigems Limited | Professional & scientific | 2007 |
| Agile Systems Australia Ltd | Information & communication | 2026 |
| Aglow Health (UK) Limited | Professional & scientific | 2001 |
| Agmd Estates Ltd | Real estate | 2022 |
| Agriculture, Estates and Rural Services Ltd | Financial services | 2025 |
| Aguila Sport UK Ltd | Administrative & support | 2019 |
| AH (Applecroft) Ltd | Professional & scientific | 2014 |
| AH Proctor Consultancy Ltd | Professional & scientific | 2023 |
| AH Residential Ltd | Real estate | 2022 |
| AH Trading MCR Ltd | Wholesale & retail | 2020 |
| Ah&Co Accountant Limited | Professional & scientific | 2020 |
| AHD MCR Constructions Limited | Construction | 2024 |
| Ahmad Bari Ltd | Transport & logistics | 2024 |
| Ahmed Brothers Ltd | Transport & logistics | 2026 |
| Ahmed Transport & Trading Ltd | Wholesale & retail | 2023 |
| AHT Property Group Limited | Real estate | 2025 |
| AI Ocean Limited | Information & communication | 2026 |
| AI RC Group Limited | Professional & scientific | 2020 |
| AI Squad Ltd | Information & communication | 2024 |
| AI7 Security Solutions Ltd | Administrative & support | 2024 |
| AIA Developments Limited | Real estate | 2022 |
| Aibury Ltd | Hospitality | 2023 |
| AIG Motors Ltd | Wholesale & retail | 2021 |
| AIG Property Management Ltd | Real estate | 2024 |
| Aigbehi Ltd | Health & social care | 2022 |
| Ainorr Ltd | Wholesale & retail | 2025 |
| Ainsley Kendrick Limited | Information & communication | 2021 |
| Ainslie Sharp Ltd | Construction | 2023 |
| Ainsworth Road Butchers Ltd | Wholesale & retail | 2019 |