| Appin Consultancy Services Limited | Professional & scientific | 2025 |
| Appin House Consulting Ltd | Professional & scientific | 2018 |
| Apple Court Management Company Limited | Households | 1991 |
| Apple Tree England Limited | Information & communication | 2022 |
| Appleby Farms Limited | Agriculture & fishing | 1986 |
| Appledore Grove Management Company Limited | Households | 2018 |
| Applesky Drones Limited | Professional & scientific | 2024 |
| Appleton Developments Limited | Construction | 2024 |
| Appleton Estates Limited | Real estate | 1995 |
| Appleton Land Limited | Real estate | 2006 |
| Appleton Piling Consultancy Ltd | Administrative & support | 2020 |
| Appletree Commercial Finance Limited | Financial services | 2018 |
| Appletree Design Solutions Ltd | Administrative & support | 2016 |
| Appletree Practice Ltd | Extraterritorial | 2007 |
| Appliance Care York & Selby Limited | Other services | 2025 |
| Applied Energistics Ltd | Information & communication | 2018 |
| Applied Experimental Ltd | Manufacturing | 2023 |
| Applied Insect Science Ltd | Professional & scientific | 2010 |
| Appnetix Limited | Information & communication | 2020 |
| Appokalyps Ltd | Information & communication | 2020 |
| Approachable Accountants Ltd | Professional & scientific | 2010 |
| Apptree Ltd | Information & communication | 2013 |
| April Louise Permanent Cosmetics Ltd | Other services | 2018 |
| APS ATC & Airport Consultancy Limited | Professional & scientific | 2018 |
| Aptamer Diagnostics Limited | Professional & scientific | 2008 |
| Aptamer Group PLC | Professional & scientific | 2014 |
| Aptamer Solutions Limited | Professional & scientific | 2012 |
| Aptamer Therapeutics Limited | Professional & scientific | 2014 |
| Aptare Properties Ltd | Real estate | 2018 |
| Aptasort Limited | Extraterritorial | 2014 |
| Aqua Solutions North Yorkshire Ltd | Construction | 2024 |
| Aqua Tiling Ltd | Construction | 2002 |
| Aqualogic Heating & Plumbing Ltd | Construction | 2026 |
| Aquarius Business Solutions LLP | | 2005 |
| Aquatread Canine Hydrotherapy Limited | Professional & scientific | 2015 |
| AR & Partners Consulting Ltd | Professional & scientific | 2016 |
| AR Pumpcrete Limited | Construction | 2022 |
| AR Tuition Limited | Education | 2024 |
| ARA Professional Ltd | Health & social care | 2025 |
| Arachna Digital Ltd | Information & communication | 2024 |
| Arah Holdings Ltd | Real estate | 2022 |
| Arah Properties Ltd | Real estate | 2025 |
| Araucaria Fine Foods Ltd | Agriculture & fishing | 2019 |
| Arbiter Limited | Professional & scientific | 2016 |
| Arbor Companies Ltd | Professional & scientific | 2024 |
| Arbpro Ltd | Information & communication | 2026 |
| ARC Education (York) Ltd | Education | 2017 |
| ARC Resolve Limited | Professional & scientific | 2020 |
| Arcanum Games Ltd | Information & communication | 2021 |
| Arch Plant Hire Ltd | Administrative & support | 2025 |
| Archaeological Management Solutions Limited | Other services | 2016 |
| Archalls Property Ltd | Real estate | 2023 |
| Archangel Investments Ltd | Real estate | 2025 |
| Archangel Roofing Ltd | Construction | 2025 |
| Archer Health and Safety Limited | Professional & scientific | 2024 |
| Archiebalds Consulting Ltd | Professional & scientific | 2025 |
| Archipod Ltd | Manufacturing | 2007 |
| Architectural & Creative Design Ltd | Professional & scientific | 2011 |
| Architectural Project Management York Ltd | Professional & scientific | 2024 |
| Architek Design & Planning Ltd | Professional & scientific | 2013 |
| Arcnova Group Limited | Real estate | 2024 |
| Arcross Limited | Extraterritorial | 2010 |
| Ardate Limited | Financial services | 2025 |
| Arden Matheson Ltd | Education | 2015 |
| Ardent Fireworks Displays Ltd | Arts & recreation | 2018 |
| Ardent Fireworks Ltd | Wholesale & retail | 2011 |
| Ardent Hawthorne Limited | Extraterritorial | 2026 |
| Ardent IFA Holding Company Ltd | Financial services | 2025 |
| Ardent IFA Limited | Financial services | 2006 |
| Ardent Law Limited | Professional & scientific | 2011 |
| Arderne Limited | Hospitality | 1991 |
| Ardoria Ltd | Information & communication | 2007 |
| ARE WE There YET? Properties Ltd. | Other services | 2023 |
| Area Marquee Hire Ltd | Other services | 2010 |
| Ares Dispute Resolution Limited | Construction | 2020 |
| Arglam Renewables Limited | Energy | 2013 |
| Argm Properties Limited | Real estate | 2024 |
| Argrain Holdings Limited | Agriculture & fishing | 2011 |
| Argrain Limited | Agriculture & fishing | 1975 |
| Argyll Stirling Wealth Management Ltd | Financial services | 2019 |
| Aria Homes Limited | Extraterritorial | 1988 |
| Aries Trade Limited | Wholesale & retail | 2025 |
| Arion HR Ltd | Professional & scientific | 2020 |
| Aristocats Cattery Limited | Professional & scientific | 2010 |
| ARK Computer Solutions Ltd | Other services | 2015 |
| ARK Givendale Ltd | Professional & scientific | 2013 |
| Arka Salon Collective Ltd | Other services | 2025 |
| Arkatect Ltd | Professional & scientific | 2019 |
| Arkle Architects Limited | Professional & scientific | 2010 |
| Arklow Engineering Limited | Professional & scientific | 2006 |
| Armac Holdings Limited | Extraterritorial | 2020 |
| Armac Veterinary Group Limited | Professional & scientific | 2006 |
| Armadillo Heating Ltd | Construction | 2024 |
| Armadillo Plumbing Ltd | Construction | 2006 |
| Armech Designs Ltd | Professional & scientific | 2012 |
| Arminson Retail Ltd | Wholesale & retail | 2020 |
| Armistead Engineering Ltd | Manufacturing | 2007 |
| Armley Amusements Limited | Other services | 2005 |
| Armonia Limited | Other services | 2000 |
| Armstrong Developers Ltd | Construction | 2021 |