| Annie Nordstrom Ltd | Information & communication | 2025 |
| ANS Group Global Holdings Limited | Financial services | 2019 |
| Ansti Consulting Ltd | Information & communication | 2016 |
| Anthropology Knowledge Associates Limited | Professional & scientific | 2022 |
| Anti Copying in Design Limited | Other services | 1997 |
| Antill & Co. Limited | Construction | 2014 |
| Antiyear Limited | Hospitality | 1987 |
| Antler Agency Limited | Professional & scientific | 2017 |
| AP22 Limited | Hospitality | 2025 |
| AP24 Limited | Hospitality | 2026 |
| Apav 232 Limited | Other services | 2023 |
| Apav 233 Limited | Other services | 2023 |
| Apav 261 Limited | Administrative & support | 2020 |
| Apav 262 Limited | Other services | 2026 |
| Apex Auto Rentals Ltd | Administrative & support | 2026 |
| Apex Guardian Ltd | Administrative & support | 2025 |
| Apex Highway Fencing Limited | Construction | 2023 |
| Apex Renovation Services Ltd | Construction | 2026 |
| Apex Scaffolding Group Ltd | Construction | 2025 |
| APEX8 Ltd | Wholesale & retail | 2013 |
| Apios Ltd | Manufacturing | 2020 |
| APJ Psychological Consulting Ltd | Health & social care | 2012 |
| Apollo Smiles Ltd | Health & social care | 2022 |
| Apollonia Sussex Ltd | Professional & scientific | 2024 |
| Appella Limited | Professional & scientific | 2004 |
| Appletree Visualization Limited | Construction | 1999 |
| Applied Drilling Intelligence Limited | Information & communication | 2020 |
| Apportal Solutions Limited | Information & communication | 2022 |
| Appro Maritime Ltd | Professional & scientific | 2023 |
| APR Innovations Ltd | Construction | 2026 |
| April Gardens Limited | Households | 2004 |
| Aprotec Instrumentation Ltd | Professional & scientific | 2011 |
| APS Growers Ltd | Agriculture & fishing | 2012 |
| APS Produce Limited | Agriculture & fishing | 1997 |
| Apuldram Farm Ltd | Construction | 2025 |
| Apuldram Farm Trading Ltd | Other services | 2026 |
| Apuldram Limited | Real estate | 2014 |
| Aqua MIX Ltd | Manufacturing | 2023 |
| Aqua Pine Ltd | Real estate | 2023 |
| Aquacair Ltd | Water & waste | 1999 |
| Aquaforge Consulting Limited | Professional & scientific | 2026 |
| Aquashine Ltd | Administrative & support | 2025 |
| Aquatherm South Limited | Construction | 2013 |
| Aragorn Hosting Ltd | Information & communication | 2025 |
| Araminta Limited | Information & communication | 2025 |
| Araz Design and Construction Ltd | Construction | 2024 |
| ARB Rangers Ltd | Agriculture & fishing | 2025 |
| Arbor Properties (Woodruff) Limited | Real estate | 2014 |
| Arboreal Woodlands Ltd | Agriculture & fishing | 2023 |
| Arbtechnic Limited | Administrative & support | 2016 |
| Arbus Group Ltd | Construction | 2018 |
| Arbus Limited | Construction | 2000 |
| ARC Electrical & Lighting Contractors Limited | Construction | 2006 |
| Archiprod Ltd | Construction | 2026 |
| Archlite Design Ltd | Information & communication | 2008 |
| Archwood Consulting Ltd | Professional & scientific | 2010 |
| Arctic Electrical South Ltd | Construction | 2026 |
| Arctic Management Limited | Information & communication | 1993 |
| Arden Sussex Ltd | Hospitality | 2024 |
| Ardentis Limited | Construction | 2014 |
| Ardhaz Designs Limited | Professional & scientific | 2016 |
| Ardy's Barbershop Ltd | Other services | 2020 |
| Argonaut Media Ltd | Information & communication | 2018 |
| Ariscroft Limited | Financial services | 2011 |
| Arista Solutions Ltd | Health & social care | 2013 |
| ARK Energy Consultancy Ltd | Professional & scientific | 2008 |
| ARK Gaming Ltd | Information & communication | 2022 |
| Arkell Floorings Ltd | Construction | 2017 |
| Arkezon Ltd | Wholesale & retail | 2023 |
| Arkle Capital Limited | Other services | 2021 |
| Arkle Estates Limited | Other services | 2015 |
| Arkle Holdings Limited | Other services | 2015 |
| Arkle Partners Limited | Other services | 2014 |
| Armitage Communications Limited | Extraterritorial | 2004 |
| Armo Architecture Ltd | Professional & scientific | 2022 |
| Armour Construction Ltd | Construction | 2014 |
| Armoured Hedgehog Ltd | Agriculture & fishing | 2023 |
| Army Dependants Assurance Trust Limited | Financial services | 1973 |
| Armydogtags Ltd | Wholesale & retail | 2013 |
| Aroschem Limited | Wholesale & retail | 2001 |
| Aroschem UK Limited | Wholesale & retail | 2009 |
| Arrant Land Limited | Construction | 2011 |
| Art Book Warehouse Limited | Extraterritorial | 2014 |
| Art Books International Ltd | Wholesale & retail | 2022 |
| Art for Preventable Extinction (UK) Ltd | Wholesale & retail | 2025 |
| Art WRD Ltd | Wholesale & retail | 2016 |
| Artemira Ltd | Professional & scientific | 2025 |
| Artful Entertainment Limited | Arts & recreation | 2024 |
| Artisan Gallery Chichester Ltd | Wholesale & retail | 2023 |
| Artius Care Ltd | Health & social care | 2015 |
| ARTY2 Ltd | Arts & recreation | 2009 |
| Arun Recycling Ltd | Water & waste | 2008 |
| Arun Valley Ltd | Wholesale & retail | 2023 |
| Arun View Limited | Real estate | 2016 |
| Arundel Chalk Springs Fishery Ltd | Other services | 2020 |
| Arundel Festival Ltd | Arts & recreation | 2024 |
| Arundel Festivals and Events Limited | Arts & recreation | 2010 |
| Arundel Trout Farm Ltd | Other services | 2020 |
| AS PBL Limited | Financial services | 2023 |
| Asap Removals and Storage Limited | Transport & logistics | 2010 |