| AO FFF Coaching LLP | | 2025 |
| AOB Support Limited | Health & social care | 2025 |
| Aosd Ltd | Information & communication | 2010 |
| AP Berrystone Building Contractors Limited | Construction | 1999 |
| AP Realty Ltd | Real estate | 2020 |
| APA Procurement Training Limited | Education | 2014 |
| Apao Property Limited | Real estate | 2025 |
| APB Softwares UK Ltd | Information & communication | 2024 |
| Apcalv LLP | | 2018 |
| APD Business Management Ltd | Professional & scientific | 2006 |
| APD Group Ltd | Professional & scientific | 2010 |
| APE House Limited | Arts & recreation | 2002 |
| Aperio Audio Visual Ltd | Construction | 2013 |
| Apex Commercial Services Ltd | Professional & scientific | 2015 |
| Apex Fuel Limited | Wholesale & retail | 2025 |
| Apex Masculine Transformations Ltd | Education | 2025 |
| Apex Properties Services Ltd | Real estate | 2025 |
| Apex Properties Swindon Ltd | Real estate | 2025 |
| Apex Scaffolding Services Swindon Limited | Construction | 2007 |
| Apex Swindon Limited | Arts & recreation | 2023 |
| APH Building Limited | Construction | 2023 |
| APH Property Group Limited | Real estate | 2023 |
| APM Automation Solutions Ltd | Professional & scientific | 2021 |
| Apolanda Properties Ltd | Real estate | 2025 |
| Apollo Solutions Wiltshire Ltd | Other services | 2023 |
| Apostrophe Books Ltd | Wholesale & retail | 2011 |
| Appetising Development Ltd | Information & communication | 2020 |
| Apple Grove Ltd | Information & communication | 2010 |
| Applewood Court Residents (Swindon) Limited | Households | 1982 |
| Applewood Stoves Ltd | Construction | 2018 |
| Applied Genetic Services Limited | Professional & scientific | 1999 |
| Applied Knowledge Systems Ltd | Information & communication | 2008 |
| Appligenics Limited | Information & communication | 1995 |
| Approachable Payroll Services Ltd | Administrative & support | 2015 |
| Approved Services Limited | Administrative & support | 2007 |
| APR Property Ltd | Real estate | 2016 |
| April Soko Ltd | Public administration | 2025 |
| Aprilco Ltd | Administrative & support | 2025 |
| APS Management Services Ltd. | Professional & scientific | 2023 |
| APS Property Limited | Real estate | 2016 |
| Apsan’S Diadem Limited | Health & social care | 2018 |
| Aptyk Limited | Financial services | 2011 |
| Aqua Boss Cleaning Services Ltd | Administrative & support | 2009 |
| Aqua G Hairdressing Limited | Other services | 2014 |
| Aqua Maintenance (UK) Limited | Wholesale & retail | 2013 |
| Aquarius Cleaning Services Limited | Administrative & support | 1976 |
| Aquatic Management Services Limited | Administrative & support | 2005 |
| Aquila Corporation UK Limited | Agriculture & fishing | 1999 |
| Aquila Hub Ltd | Wholesale & retail | 2024 |
| AR Alton Ltd | Construction | 2025 |
| AR Electrical South Ltd | Energy | 2024 |
| AR Estate Group Ltd | Real estate | 2025 |
| AR Venues Ltd | Hospitality | 2024 |
| Aradrylining Ltd | Construction | 2020 |
| Aragla Ltd | Wholesale & retail | 2018 |
| Arah Perrett Consultancy Ltd | Professional & scientific | 2018 |
| Aramac Limited | Wholesale & retail | 2012 |
| ARB2EARTH Contracting Ltd | Construction | 2026 |
| Arbani Impex Ltd | Wholesale & retail | 2025 |
| Arbgrow Limited | Wholesale & retail | 2023 |
| Arbutus Technical Consulting Limited | Professional & scientific | 2007 |
| ARC Care Ltd | Health & social care | 2020 |
| ARC Insulations Ltd | Construction | 2024 |
| ARC IT Consultancy Ltd | Information & communication | 2016 |
| Arcadian Ventures Limited | Administrative & support | 2022 |
| Arcadius Group Ltd | Professional & scientific | 2023 |
| Arch Serve Limited | Other services | 2013 |
| Archaeological Management Services Limited | Professional & scientific | 1997 |
| Archair Limited | Energy | 2022 |
| Archer and Smith Holdings Limited | Professional & scientific | 2018 |
| Archer and Smith Limited | Manufacturing | 1961 |
| Archer Data Solutions Ltd | Information & communication | 2023 |
| Archer Hydraulic Services Limited | | 1985 |
| Archer Retail Ltd | Wholesale & retail | 2025 |
| Archers Heating & Plumbing Limited | Construction | 2012 |
| Archers Recruitment Limited | Administrative & support | 2003 |
| Archie's Sons Ltd | Hospitality | 2021 |
| Archilux Ltd | Construction | 2022 |
| Archipelago Online Ltd | Manufacturing | 2024 |
| Arctic Services (Swindon) Limited | Administrative & support | 2002 |
| Arcturus Strategy Ltd | Professional & scientific | 2026 |
| ARCTURUS37 Ltd | Administrative & support | 2024 |
| Arcwood Interiors Ltd | Wholesale & retail | 2022 |
| Ardeodom Limited | Real estate | 2025 |
| Ardil Capital Limited | Real estate | 2026 |
| Ardle Bank Limited | Households | 2019 |
| Arena Interior Design and Development Limited | Construction | 2011 |
| Arete Project Solutions Limited | Professional & scientific | 2025 |
| ARG Software Consultancy Ltd | Information & communication | 2012 |
| Argante Care Limited | Health & social care | 2014 |
| Arham Consultants Ltd | Professional & scientific | 2019 |
| Aria Financial Limited | Financial services | 2019 |
| Ariadne Road RTM Company Limited | Households | 2008 |
| Arian Transport Ltd | Transport & logistics | 2024 |
| Arielite Ltd | Transport & logistics | 2024 |
| Aries & Taurus Ltd | Manufacturing | 2025 |
| Aries Films Limited | Information & communication | 2019 |
| Aries Media Limited | Information & communication | 2006 |
| Arisa Global Ltd | Transport & logistics | 2023 |
| ARJ Rentals Ltd | Real estate | 2016 |