| Arklight Technology Ltd | Information & communication | 2022 |
| Arksey Mini Mart Limited | Wholesale & retail | 2015 |
| Arlo J Holdings Ltd | Wholesale & retail | 2018 |
| Armani Express Limited | Wholesale & retail | 2024 |
| Armatek Ltd | Construction | 2023 |
| Armitage Bros Ltd | Real estate | 2024 |
| Armstrongs Auto Services Ltd | Wholesale & retail | 2010 |
| Arnold Murati Technical Services Ltd | Manufacturing | 2021 |
| ARO Utilities Ltd | Construction | 2024 |
| Arole Ltd | Hospitality | 2025 |
| Aroma World Limited | Manufacturing | 2009 |
| Around the Globe Travel Ltd | Administrative & support | 2016 |
| Arrow Contracting Ltd | Financial services | 2017 |
| Arrow Dental Limited | Health & social care | 2025 |
| Arrow Speedy Deliveries Ltd | Transport & logistics | 2023 |
| Arrow Technical Services Limited | Manufacturing | 1995 |
| Arrowzone Limited | Manufacturing | 1986 |
| Arrys Construction Limited | Construction | 2025 |
| Art 3 Airport Transfers Ltd | Transport & logistics | 2019 |
| Art Music Limited | Information & communication | 2011 |
| Art Music Records Ltd | Information & communication | 2021 |
| Art Works South Yorkshire Ltd | Health & social care | 2019 |
| Art.Sho Ltd | Arts & recreation | 2022 |
| Artez BJJ Ltd | Arts & recreation | 2022 |
| Artforest Ltd | Manufacturing | 2015 |
| Arthur Rose Recruitment Ltd | Administrative & support | 2020 |
| Artisan Ales International Ltd | Wholesale & retail | 2019 |
| Artisan Sintered Products Limited | Manufacturing | 1967 |
| Artisan Spirits International Limited | Professional & scientific | 2007 |
| Artisan View Management Company Limited | Households | 2023 |
| Artistchoice Limited | Arts & recreation | 1995 |
| Artistmap Limited | Information & communication | 2005 |
| Artunum Limited | Information & communication | 2022 |
| Arturo Ltd | Transport & logistics | 2020 |
| Arundel Lane Studios Ltd | Arts & recreation | 2026 |
| Arya Arnav Limited | Information & communication | 2013 |
| Aryaadamplatinum UK Ltd | Other services | 2022 |
| Aryan Property Group Ltd | Real estate | 2023 |
| AS Ophthalmic Ltd | Professional & scientific | 2005 |
| AS Building Services Rotherham Ltd | Construction | 2026 |
| AS Transporters Limited | Transport & logistics | 2019 |
| Asa.Cateringuk Ltd | Hospitality | 2023 |
| Asadify X Limited | Extraterritorial | 2024 |
| Asagma Investments Ltd | Real estate | 2025 |
| Asap International Freight Limited | Transport & logistics | 1996 |
| Asbestos Network Ltd | Wholesale & retail | 2026 |
| Ascot Taxis Limited | Transport & logistics | 2008 |
| Ascotwalk Limited | Real estate | 1978 |
| ASD Lighting Holdings Limited | Professional & scientific | 2009 |
| ASD Lighting PLC | Manufacturing | 1982 |
| ASD Management (Rotherham) LLP | | 2010 |
| ASELECTRICAL22 Ltd | Construction | 2023 |
| Asfalis Ltd | Information & communication | 2006 |
| ASG Civils Ltd | Construction | 2022 |
| ASG Developments Limited | Real estate | 2004 |
| ASG Locksmith Limited | Administrative & support | 2025 |
| ASH Electrical Services Limited | Construction | 2023 |
| Asha Studio Limited | Arts & recreation | 2025 |
| Ashe Electrical Contractors Ltd | Construction | 2020 |
| Asher Developments Ltd | Construction | 2021 |
| Ashfield Aromatherapy Limited | Extraterritorial | 1993 |
| Ashgas Ltd | Construction | 2018 |
| Ashh Services Limited | Health & social care | 2020 |
| Ashlight Limited | Health & social care | 2013 |
| Ashmm Khawla Property's Limited | Real estate | 2026 |
| Ashmm Limited | Wholesale & retail | 2025 |
| Ashmore Financial Services Ltd | Financial services | 2006 |
| Ashwhit Ltd | Wholesale & retail | 2019 |
| ASJ Limited | Hospitality | 2026 |
| ASK 4 Plumbing and Heating Services Limited | Construction | 2018 |
| ASK Recruiting Limited | Administrative & support | 2021 |
| Askado Group Ltd | Information & communication | 2015 |
| Askwiki Ltd | Information & communication | 2025 |
| Aslam Investment Group Ltd | Administrative & support | 2017 |
| ASM Machinery Limited | Wholesale & retail | 2025 |
| Asotml Limited | Other services | 2020 |
| Aspect International Group Limited | Wholesale & retail | 2022 |
| Aspen Lodges Ltd | Manufacturing | 2018 |
| Aspire Fire Protection Ltd | Construction | 2024 |
| Aspire Properties Limited | Real estate | 2024 |
| Aspire Sports Therapy and Massage Limited | Other services | 2018 |
| Assembi Security Bars Ltd | Construction | 2017 |
| Asset Finance and Refinance Limited | Financial services | 2015 |
| Asset Performance Consultants Limited | Information & communication | 2020 |
| ASSET66 Ltd | Administrative & support | 2023 |
| Assisted Ways Limited | Transport & logistics | 2021 |
| Associate VIS Ltd | Administrative & support | 2015 |
| Associated Transport Limited | Transport & logistics | 2023 |
| Association of Education Business Professionals C.I.C. | Education | 2018 |
| Association of University Engineers | Education | 2016 |
| Assured Autoclave Services Ltd | Other services | 2005 |
| Assured Decontamination Services Limited | Other services | 2026 |
| Assured Equity Finance Ltd | Financial services | 2020 |
| Asti Hire Limited | Construction | 1977 |
| Aston Facility Management Ltd | Wholesale & retail | 2024 |
| AT Building Systems Ltd | Construction | 2020 |
| AT Drylining Limited | Construction | 2022 |
| AT Sales Ltd | Wholesale & retail | 2025 |
| AT Social Media Limited | Professional & scientific | 2015 |
| AT TV Ltd | Information & communication | 2022 |