| Adur River Homes Ltd | Real estate | 2026 |
| Advance Guarding Ltd | Administrative & support | 2007 |
| Advanced Care Rentals Limited | Professional & scientific | 1990 |
| Advanced Plumbing Solutions Ltd | Construction | 2021 |
| Advanced Polymers Limited | Manufacturing | 1974 |
| Advanced Power Services Limited | Construction | 2010 |
| Advanced Spares Limited | Extraterritorial | 2022 |
| Advantec Consulting Limited | Information & communication | 2003 |
| Advantus Group Limited | Professional & scientific | 2004 |
| Aegis Security Consulting Limited | Information & communication | 2021 |
| Aelia Collection Limited | Wholesale & retail | 2019 |
| Aerial Fitness Studios Ltd | Arts & recreation | 2026 |
| Aero Sekur Airborne Limited | Professional & scientific | 2017 |
| Aero Trading Ltd | Wholesale & retail | 2019 |
| Aerotyne Training Solutions Ltd | Education | 2024 |
| Aesthetics by Elizabeth Limited | Health & social care | 2022 |
| Aetas Management Ltd | Administrative & support | 2014 |
| AF Osteopathy & Sports Injury Limited | Health & social care | 2013 |
| Affirmation Limited | Health & social care | 2018 |
| Affordable Flooring Limited | Construction | 2017 |
| AFG Solutions Limited | Real estate | 2018 |
| Afsw Consults Ltd | Health & social care | 2025 |
| After Chaos Limited | Manufacturing | 2026 |
| After Party Studios Limited | Information & communication | 2016 |
| AG Bookkeeping Services Ltd | Professional & scientific | 2018 |
| AG Conversions Limited | Construction | 2021 |
| AG Sales and Consulting Ltd. | Administrative & support | 2015 |
| AG Treatment Rooms Ltd | Other services | 2023 |
| AGB West Sussex Limited | Real estate | 2022 |
| AGD Consulting Limited | Professional & scientific | 2013 |
| Agency Stack UK Limited | Professional & scientific | 2021 |
| Agenx Partners Ltd | Information & communication | 2024 |
| Agility Healthcare Ltd | Other services | 2011 |
| AGP Consultants Limited | Professional & scientific | 2014 |
| AGS Talent Ltd | Information & communication | 2021 |
| Ahead Loft Ladders Ltd | Construction | 2015 |
| AHG Holdings Limited | Financial services | 2023 |
| AHG Property Holdings Limited | Real estate | 2021 |
| Ahmed Rashid Worthing Ltd | Hospitality | 2025 |
| Aiddia Ltd | Professional & scientific | 2017 |
| Aidek Contract Services Ltd | Administrative & support | 2018 |
| AIM Troncmasters Ltd | Information & communication | 2024 |
| Aimee Betts Ltd | Manufacturing | 2023 |
| Aims Global Group Ltd | Professional & scientific | 2026 |
| Aintree House Lease Holdings Limited | Real estate | 2024 |
| AIO Fusion Limited | Information & communication | 2026 |
| Airconcompany Limited | Construction | 2018 |
| Aireborne Ltd | Administrative & support | 2018 |
| Aitmatech Limited | Information & communication | 2025 |
| Aivgo Limited | Extraterritorial | 2012 |
| AJ Ashby Limited | Administrative & support | 2017 |
| AJC Contractors (South East) Ltd | Construction | 2009 |
| AJD Management Ltd | Administrative & support | 2024 |
| Ajda Properties Limited | Real estate | 2021 |
| AJF Flooring Limited | Construction | 2008 |
| AJI and Aksh Ltd | Wholesale & retail | 2018 |
| AJS Engineering (South) Ltd | Construction | 2026 |
| AK Final Countdown Limited | Financial services | 2023 |
| AK Music Ltd | Arts & recreation | 2017 |
| Akanni Group Limited | Arts & recreation | 2019 |
| Akarei Limited | Wholesale & retail | 2025 |
| Akari Therapeutics, PLC | Administrative & support | 2004 |
| Akhstar Ltd | Information & communication | 2024 |
| AKM Builders Ltd | Construction | 2019 |
| Akord Ltd | Information & communication | 2025 |
| AKP Property Management Ltd | Real estate | 2026 |
| Aktivworld Ltd | Construction | 2016 |
| AL Electrical Ltd | Construction | 2017 |
| AL Logistic Ltd | Transport & logistics | 2026 |
| Alan Lindfield Limited | Transport & logistics | 1997 |
| Alan Mcdermott Books Limited | Information & communication | 2013 |
| Alan Zada Ltd | Arts & recreation | 2026 |
| Alan’S Bahar Kebab Ltd | Hospitality | 2023 |
| Alarm PT Limited | Manufacturing | 2025 |
| Albakos Holding Ltd | Real estate | 2026 |
| Albanese Consulting Limited | Professional & scientific | 2017 |
| Albd Investments Limited | Real estate | 2023 |
| Albec Roofing Limited | Construction | 2020 |
| Albigny LLP | | 2016 |
| Albion Ships Agents Limited | Other services | 1994 |
| ALBION8753 Ltd | Construction | 2021 |
| Alborz Limited | Administrative & support | 2012 |
| Alcina Associates Ltd | Professional & scientific | 2022 |
| ALD Solutions Ltd | Manufacturing | 2025 |
| Alderney Court (Management) Limited | Households | 2004 |
| Aldway Stamping Ltd | Extraterritorial | 1912 |
| Aldway(Dbb) Limited | Professional & scientific | 1934 |
| Aleph-Null Ltd | Information & communication | 2025 |
| Alex Cladding Limited | Other services | 2019 |
| Alex Jordan Performance Ltd | Arts & recreation | 2025 |
| Alex Property Development Ltd | Real estate | 1989 |
| Alexander Kitchens Limited | Wholesale & retail | 2021 |
| Alexander Philips & Welch LLP | | 2024 |
| Alexander Philips Limited | Real estate | 2009 |
| Alexandra & Church Ltd | Real estate | 2025 |
| Alexandra Properties (Worthing) Limited | Households | 2010 |
| Alexsca Investments Ltd | Real estate | 2019 |
| Alf's Motorcycles Limited | Wholesale & retail | 2006 |
| Alfen Medical Devices Development Ltd | Professional & scientific | 2020 |
| ALI Baba Cutz Ltd | Other services | 2025 |