| Armada Fleet Repair Ltd | Wholesale & retail | 2024 |
| Armor Property Ltd | Real estate | 2025 |
| Armour Media Ltd | Manufacturing | 2019 |
| ARN Patton Property Limited | Real estate | 2017 |
| Arna Properties Ltd | Real estate | 2018 |
| Arnvik IT Ltd | Information & communication | 2016 |
| Arora Cars Private Ltd | Transport & logistics | 2024 |
| Arrival Systems Ltd | Information & communication | 2026 |
| Arrizon UK Ltd | Wholesale & retail | 2025 |
| Art Inc CIC | Education | 2022 |
| Artecleaning Ltd | Administrative & support | 2020 |
| Artemisia Gold CIC | Education | 2023 |
| Arthur and Conway Accountants Ltd | Professional & scientific | 2014 |
| Artists World Limited | Wholesale & retail | 2025 |
| Artius DRY Risers Limited | Administrative & support | 2023 |
| Artius Fire Protection Limited | Other services | 2021 |
| Artius Holdings Limited | Other services | 2022 |
| Artius Property Protection Limited | Financial services | 2015 |
| Artsy Home Limited | Wholesale & retail | 2020 |
| Artyzan Group Limited | Construction | 2022 |
| Aruljothy Ltd | Other services | 2017 |
| Arun Technology Ltd | Manufacturing | 2005 |
| Arundel and Brighton Lourdes Pilgrimage Limited | Administrative & support | 1994 |
| Arundel and Brighton Roman Catholic Diocesan Corporation Limited(The) | Other services | 1969 |
| ARV Properties Ltd | Real estate | 2026 |
| Arvion Workforce Ltd | Wholesale & retail | 2025 |
| Arxis SP Limited | Administrative & support | 2011 |
| Aryan Produce Ltd | Manufacturing | 2018 |
| AS (Sussex) Retail Ltd. | Wholesale & retail | 2004 |
| AS Associates Management and Quality Ltd | Professional & scientific | 2026 |
| AS Dream Homes Ltd | Real estate | 2024 |
| AS Enterprise Crawley Ltd | Hospitality | 2024 |
| As&U Ltd | Professional & scientific | 2026 |
| ASA Briggs Ltd | Real estate | 2022 |
| Asad Khan Ltd | Transport & logistics | 2020 |
| Asavonne Services Limited | Construction | 2020 |
| Asba Accounting Ltd | Professional & scientific | 2017 |
| Asba Digital Ltd | Professional & scientific | 2026 |
| Ascending Mindset Limited | Other services | 2025 |
| Ascension Specialist Limited | Health & social care | 2012 |
| Ascent Logistics Ltd | Transport & logistics | 2021 |
| Ascn Holdings Ltd | Construction | 2022 |
| Asentia Ltd | Information & communication | 2026 |
| ASF Consulting Ltd | Agriculture & fishing | 2017 |
| ASF Logistic Limited | Wholesale & retail | 2024 |
| ASG Dunamis Relocations Ltd. | Extraterritorial | 2022 |
| Ashapuri Corporation Limited | Wholesale & retail | 2019 |
| Ashcroft Automations Ltd | Information & communication | 2026 |
| Ashlake (London) Limited | Real estate | 2017 |
| Ashmik Services Ltd | Health & social care | 2023 |
| Asona Consulting Ltd | Health & social care | 2020 |
| Aspect Construction (South East) Limited | Construction | 2019 |
| Aspire Global Pathways Ltd | Education | 2024 |
| Aspire Inst Limited | Education | 2024 |
| Aspire Learning Solutions Ltd | Administrative & support | 2015 |
| Association of Immigrants | Other services | 2009 |
| Assumed Form Ltd | Manufacturing | 2021 |
| AST Groups Limited | Real estate | 2021 |
| Astraeus Services Ltd | Manufacturing | 2024 |
| Astrapet Limited | Extraterritorial | 1992 |
| Asus Construction Limited | Extraterritorial | 2021 |
| Asus Developments Limited | Extraterritorial | 2021 |
| Asus Energy Limited | Construction | 2025 |
| Asya Mind & Body Wellbeing Ltd | Education | 2026 |
| ATA Building & Maintenance Services Ltd | Other services | 2019 |
| Atelier 21 Ltd | Education | 2020 |
| ATG Marley Transport Ltd | Transport & logistics | 2018 |
| Athena B Ltd | Hospitality | 2024 |
| Atherton Bailey Limited | Other services | 2014 |
| ATJ Rowfant Vehicle Inspection Centre Ltd | Manufacturing | 2026 |
| Atlantic Consultancy Solutions Ltd | Information & communication | 2015 |
| Atlantiko Ltd. | Wholesale & retail | 2016 |
| Atlas Cars Crawley Ltd | Transport & logistics | 2013 |
| Atlas MED Rescue Ltd | Health & social care | 2024 |
| Atmos Living Ltd | Construction | 2023 |
| Atoll Design Limited | Manufacturing | 2018 |
| Atomicai Limited | Information & communication | 2025 |
| Atpd Consulting Ltd | Information & communication | 2016 |
| Atpd Property Management Ltd | Real estate | 2018 |
| ATT Walters Limited | Manufacturing | 2015 |
| Audit Wise Limited | Information & communication | 2023 |
| Aura Biosearch Ltd | Administrative & support | 2024 |
| Aura Electrical Limited | Construction | 2020 |
| Aura Used Cars Ltd | Wholesale & retail | 2025 |
| Aurelian Manor Ltd | Real estate | 2025 |
| Aurelius Property Ltd | Real estate | 2024 |
| Aureus Hospitality Ltd | Professional & scientific | 2025 |
| Aurevia Healthcare Limited | Administrative & support | 2026 |
| Auron Convert Limited | Professional & scientific | 2025 |
| Austin Luce & Co. Limited | Arts & recreation | 1976 |
| Authentic Stats Ltd | Information & communication | 2023 |
| Authentic-Goods Ltd | Wholesale & retail | 2022 |
| Authenticity and Associates Limited | Professional & scientific | 2018 |
| Authenticus Ltd | Manufacturing | 2018 |
| Auto AEM Limited | Professional & scientific | 2016 |
| Auto Electronics UK Solutions Ltd | Wholesale & retail | 2016 |
| Auto Key Angel Ltd | Wholesale & retail | 2024 |
| Auto Tech Gatwick Ltd | Wholesale & retail | 2026 |
| Auto Tickles Ltd | Wholesale & retail | 2026 |
| Auto Torque Ltd | Wholesale & retail | 2024 |