| Arden Consultants Ltd | Information & communication | 2026 |
| Ardenassets Ltd | Real estate | 2026 |
| Ardingly Aesthetics Limited | Health & social care | 2021 |
| Ardington Hotel Limited | Hospitality | 2012 |
| Area Management Solutions Limited | Professional & scientific | 2011 |
| Arennails Ltd | Wholesale & retail | 2023 |
| Ares European Real Estate Fund II (Euro), L.P. | | 2004 |
| Ares European Real Estate Fund III (Euro), L.P. | | 2007 |
| Arghan Capital Limited | Financial services | 2018 |
| Argos Productions Ltd | Arts & recreation | 2023 |
| Argyll Mews (Worthing) Limited | Real estate | 2017 |
| Arhea UK Limited | Professional & scientific | 2017 |
| Aria Kabul Limited | Hospitality | 2025 |
| Ariel Court (Lancing) Residents Company Limited | Households | 1993 |
| ARK PR Limited | Arts & recreation | 2012 |
| ARK SRK Ltd | Wholesale & retail | 2022 |
| Arki Studios Ltd | Information & communication | 2022 |
| Arlington Tax Limited | Professional & scientific | 2017 |
| ARM Marquees Limited | Administrative & support | 2004 |
| Armadillo Risk Management Ltd | Information & communication | 2015 |
| Armadillo Software Ltd | Information & communication | 2019 |
| Armitaj Property Ltd | Real estate | 2026 |
| Armoured for Life Ltd | Health & social care | 2018 |
| Arms Ventures Limited | Financial services | 2023 |
| Armsconstruction Limited | Manufacturing | 2025 |
| Armshouse TV Ltd | Information & communication | 2013 |
| Armston Properties Limited | Professional & scientific | 1998 |
| Armur Ltd | Construction | 2024 |
| Arquebus Ltd | Construction | 2021 |
| Arrival Productions Limited | Arts & recreation | 2010 |
| Arrow Services Ltd | Professional & scientific | 2024 |
| Arscott Systems Limited | Professional & scientific | 2014 |
| Art, Mind & Soul C.I.C. | Health & social care | 2025 |
| Artagent Limited | Education | 2002 |
| Artbiscus Limited | Information & communication | 2022 |
| Artcube Limited | Arts & recreation | 2014 |
| Arteche UK Limited | Manufacturing | 2022 |
| Artelium Limited | Agriculture & fishing | 2023 |
| Artelium Wine Estate LLP | | 2019 |
| Artery-Crea Limited | Information & communication | 2008 |
| Arthur G. Sparks (Sussex) Limited | Construction | 1971 |
| Arthurs Property Services Ltd | Real estate | 2024 |
| Artifex Gold International Limited | Wholesale & retail | 2016 |
| Artifex Gold Limited | Extraterritorial | 2015 |
| Artifice Design Limited | Administrative & support | 2003 |
| Artists Open Houses Limited | Information & communication | 2005 |
| Arun Adur Fencing Limited | Construction | 2022 |
| Arun Control Systems Limited | Information & communication | 2000 |
| Arun Forktrucks Limited | Wholesale & retail | 2007 |
| Arun Kitchen Studio Limited | Construction | 2025 |
| Arun Valley Vineyard LLP | | 2024 |
| Arundel Court (Ferring) Management Limited | Households | 1971 |
| Arundel Exterior Cleaning Limited | Administrative & support | 2022 |
| Arundel Jailhouse Ltd | Hospitality | 2011 |
| Arundel Lodge RTM Company Limited | Extraterritorial | 2025 |
| Arundel Property Services Limited | Administrative & support | 2022 |
| Arvensis Limited | Professional & scientific | 2020 |
| AS Cleaning Solutions Limited | Administrative & support | 2011 |
| AS Electrical & Data Ltd | Construction | 2025 |
| AS Roofingltd Ltd | Construction | 2026 |
| ASA International Group PLC | Financial services | 2018 |
| Ascent Support Ltd | Administrative & support | 2023 |
| Ascots and Chapels (England) Limited | Extraterritorial | 2011 |
| ASF Accountancy Services Limited | Professional & scientific | 2004 |
| ASH Joinery Limited | Manufacturing | 1999 |
| Ashbourne Group Limited | Health & social care | 1994 |
| Ashbrook Construction and Interiors Ltd | Construction | 2022 |
| Ashdown Garden Buildings Limited | Administrative & support | 2021 |
| Ashdown Hove Limited | Households | 2004 |
| Ashdown Property Investors Ltd | Real estate | 2019 |
| Ashes With Art Ltd | Manufacturing | 2017 |
| Ashleigh's Aesthetics Ltd | Health & social care | 2021 |
| Ashley James Group Limited | Construction | 2022 |
| Ashley James Meat Company Holdings Ltd | Administrative & support | 2019 |
| Ashley James Meat Company Limited | Administrative & support | 2017 |
| Ashley Paddick Limited | Health & social care | 2026 |
| Ashley Project Solutions Ltd | Construction | 2022 |
| Ashra K Limited | Hospitality | 2026 |
| Ashton-Jones Group Limited | Information & communication | 2024 |
| Ashurst Logistics Ltd | Transport & logistics | 2020 |
| Ashvale Investments Limited | Real estate | 1997 |
| Ashwood Pembroke Limited | Real estate | 2026 |
| Ashwood Resourcing Limited | Administrative & support | 2019 |
| Asiamate Limited | Wholesale & retail | 2025 |
| ASK James Ltd | Professional & scientific | 2026 |
| Aslc Property Ltd | Real estate | 2016 |
| ASM Ceilings and Partitions Ltd | Construction | 2024 |
| Asma Aquatics Ltd | Professional & scientific | 2025 |
| ASP Property Developments Limited | Construction | 2014 |
| Aspect Renovations Limited | Construction | 2017 |
| Aspectfinal Property Management Limited | Households | 1995 |
| Aspects (Goring) Management Company Limited | Real estate | 2013 |
| Aspects Management Services Limited | Real estate | 2016 |
| Aspel Leisure Ltd | Hospitality | 2025 |
| Aspem Limited | Administrative & support | 2007 |
| Aspen Court Residents Limited | Households | 2008 |
| Asphaleia Limited | Health & social care | 1999 |
| Aspire Life Care Limited | Health & social care | 2013 |
| Asrr Co Limited | Other services | 2022 |
| Asrr Rentals Ltd | Real estate | 2024 |