| Ace Brickwork and Scaffold Ltd | Construction | 2025 |
| Ace Cctv Reports Ltd | Professional & scientific | 2023 |
| Ace Facilities Ltd | Construction | 2018 |
| Ace Group (Southeast) Limited | Construction | 2020 |
| Ace Roofing Solutions Sussex Ltd | Construction | 2024 |
| Ace Scaffolding Contractors Ltd | Construction | 2018 |
| Acemark Aluminium Fabrications Limited | Construction | 2013 |
| Acemark Glazing Ltd | Construction | 2021 |
| Acemark Investments Limited | Real estate | 2026 |
| Acena Systems Ltd | Information & communication | 2022 |
| Acenteus Business Technologies Ltd. | Professional & scientific | 2022 |
| Acenteus CCA Global Ltd | Professional & scientific | 2024 |
| ACF Ltd | Water & waste | 2023 |
| Achieve UN Limited | Administrative & support | 2017 |
| Achieving Potential Ltd | Health & social care | 2024 |
| Achilles Foot Clinic Limited | Administrative & support | 2018 |
| Acies Cleaning & Support Services Limited | Administrative & support | 2015 |
| ACM Surveying & Consultancy Ltd | Water & waste | 2019 |
| ACM Test Ltd | Professional & scientific | 2022 |
| Acme (Brighton) Ltd. | Administrative & support | 2005 |
| Acorn Financial Solutions Limited | Professional & scientific | 1998 |
| Acornrent Limited | Real estate | 1991 |
| ACP Trading Limited | Wholesale & retail | 2015 |
| Acquisition Technologies Ltd | Professional & scientific | 2025 |
| Acre Build Limited | Construction | 2023 |
| Acre Landscapes Investments Limited | Real estate | 2024 |
| Acre Landscapes Limited | Administrative & support | 2008 |
| Acre Shepherd's Huts Limited | Hospitality | 2025 |
| Across Rainbows C.I.C. | Other services | 2020 |
| Across Rainbows Productions Limited | Hospitality | 2022 |
| Acsel Advisors Limited | Financial services | 2003 |
| Acti Consulting Limited | Financial services | 2015 |
| Action Bikes Brighton Limited | Wholesale & retail | 2010 |
| Activation Therapy and Case Management Ltd | Health & social care | 2017 |
| Active Kampers Ltd | Administrative & support | 2011 |
| Active Lightworks, Ltd | Health & social care | 2006 |
| Actonx Services and Construction Limited | Water & waste | 2019 |
| Actually CIC | Arts & recreation | 2009 |
| Acume International Ltd | Information & communication | 2020 |
| Acumen Multimedia Limited | Information & communication | 1999 |
| Acuvivo Medical Writing Limited | Other services | 2021 |
| Acwong Limited | Information & communication | 2014 |
| AD Dental Limited | Real estate | 2018 |
| AD Gully Construction Limited | Construction | 2016 |
| AD Maiora Ltd | Information & communication | 2016 |
| AD Williams Brighton Limited | Wholesale & retail | 2018 |
| AD Williams Crawley Limited | Wholesale & retail | 2000 |
| AD Williams Enfield Limited | Wholesale & retail | 2020 |
| AD Williams Express Heathrow Limited | Wholesale & retail | 2017 |
| AD Williams Express Limited | Wholesale & retail | 2016 |
| AD Williams Farnham Limited | Wholesale & retail | 2019 |
| AD Williams High Wycombe Limited | Wholesale & retail | 1974 |
| AD Williams Wimbledon Limited | Wholesale & retail | 2014 |
| AD Williams Worthing Limited | Wholesale & retail | 2015 |
| ADA 72 Limited | Hospitality | 2021 |
| Adal Marketing Ltd | Wholesale & retail | 2024 |
| Adam K Transport Limited | Transport & logistics | 2025 |
| Adam King Limited | Information & communication | 2012 |
| Adam LEE Web Services Limited | Information & communication | 2020 |
| Adam Lock Limited | Information & communication | 2023 |
| Adam Maca Boxing Ltd | Arts & recreation | 2025 |
| Adam Percussion Ltd | Information & communication | 2013 |
| Adam Turnbull Animation Ltd | Arts & recreation | 2021 |
| Adams Clinical Nutrition Ltd | Manufacturing | 2024 |
| Adaptive Technologies Limited | Information & communication | 1998 |
| Adar Diamond Expertise Ltd | Wholesale & retail | 2017 |
| ADB Rail Consulting Ltd | Professional & scientific | 2019 |
| Adcee Ltd | Information & communication | 2018 |
| Addactive Limited | Information & communication | 2006 |
| Addax Film Productions Limited | Professional & scientific | 1980 |
| Added Bytes Ltd | Information & communication | 2012 |
| Addiction Link Ltd | Health & social care | 2018 |
| Addictive Arts C.I.C. | Education | 2023 |
| Addictive Television Limited | Arts & recreation | 1992 |
| Adding IT UP Ltd | Professional & scientific | 2023 |
| Adele's Emporium Ltd | Wholesale & retail | 2024 |
| Adelfia Brighton Limited | Hospitality | 2016 |
| Adella Construction Limited | Construction | 2007 |
| Aden Transport Ltd | Transport & logistics | 2022 |
| Adenstar Aviation Limited | Construction | 2013 |
| Adenstar Developments Limited | Construction | 1982 |
| Adenstar Limited | Construction | 2013 |
| Adenstar Projects Limited | Construction | 1998 |
| Adenstar SPV1 Limited | Extraterritorial | 1988 |
| Adept Occupational Health Ltd | Health & social care | 2018 |
| Adeptis Group Partnership Ltd | Administrative & support | 2016 |
| ADG Marsh Consulting Limited | Professional & scientific | 2023 |
| Adgh Media Ltd | Information & communication | 2017 |
| Adhyata Invest Limited | Real estate | 2020 |
| ADI BTL Ltd | Real estate | 2021 |
| Adlite Electrical Services Ltd | Energy | 2024 |
| Admin Army UK Limited | Professional & scientific | 2020 |
| Admirable Locksmiths Limited | Administrative & support | 2004 |
| Adonis Acquisitions Ltd | Financial services | 2013 |
| Adonis Cabaret Limited | Arts & recreation | 2002 |
| Adore Outdoor Living Ltd | Construction | 2026 |
| Adrageous Media Limited | Professional & scientific | 2025 |
| Adrian Koenig Ltd | Professional & scientific | 2020 |
| Adrian Marciante Limited | Administrative & support | 2008 |
| Adrian Robins Upholstery Ltd | Other services | 2003 |