| Abef Holdings Limited | Financial services | 2012 |
| Abelo Ltd | Wholesale & retail | 2014 |
| Aberdeen Enterprise Finance Limited | Financial services | 2008 |
| ABG York Limited | Professional & scientific | 2016 |
| Abigail Yeates Architect Limited | Professional & scientific | 2022 |
| Abingdon Analytical Limited | Manufacturing | 2024 |
| Abingdon Health PLC | Manufacturing | 2008 |
| Able Carers Limited | Health & social care | 2014 |
| Able-To-Enable Limited | Wholesale & retail | 1998 |
| Abloom Limited | Administrative & support | 2005 |
| Abode Developments & Management Ltd | Real estate | 2021 |
| Abode Pads Ltd | Real estate | 2021 |
| Aboubakr Smile Care Ltd | Health & social care | 2026 |
| Abra-Weld Limited | Wholesale & retail | 2025 |
| ABS Laboratories Holdings Limited | Professional & scientific | 2020 |
| ABS Laboratories Limited | Professional & scientific | 2020 |
| Absolute Sales and Purchasing Ltd | Wholesale & retail | 2016 |
| Absolute Signalling Limited | Professional & scientific | 2011 |
| Absolute Truth Limited | Extraterritorial | 2024 |
| Abundantia Law Ltd | Professional & scientific | 2025 |
| AC Employment Limited | Administrative & support | 2019 |
| AC Energy Ltd | Construction | 2022 |
| AC Engineering (York) Limited | Professional & scientific | 2018 |
| AC Food York Ltd | Wholesale & retail | 2024 |
| AC Marine Consultants Ltd | Professional & scientific | 2021 |
| Academy Network Services Ltd | Information & communication | 2008 |
| Acandis UK Limited | Manufacturing | 2022 |
| Acaster Forge Ltd | Manufacturing | 2015 |
| Acaster Homes Limited | Manufacturing | 2014 |
| Acaster Lake Management Limited | Households | 1992 |
| Acaster Lane Management Company Limited | Households | 1991 |
| Acaster Marine Limited | Wholesale & retail | 2010 |
| Acaster Properties Limited | Construction | 2010 |
| Acaster Steel Limited | Wholesale & retail | 1990 |
| Acaster Windows Ltd | Construction | 2020 |
| Access Building Products Group Limited | Manufacturing | 2026 |
| Access Building Products Limited | Wholesale & retail | 2006 |
| Accessible Arts & Media | Arts & recreation | 1998 |
| Acclimation Ltd | Professional & scientific | 2019 |
| Accomodation 4 YOU Limited | Real estate | 2017 |
| According to Mcgee Limited | Professional & scientific | 2015 |
| Accountancy Business Support Limited | Professional & scientific | 2006 |
| Accountancy International Limited | Professional & scientific | 2016 |
| Accountants Advice Limited | Professional & scientific | 2006 |
| Accounting for Your Profit Ltd | Professional & scientific | 2021 |
| Accretis Ltd | Professional & scientific | 2011 |
| Accuvet Limited | Administrative & support | 2019 |
| Ace Commercials Limited | Wholesale & retail | 2024 |
| Acente Ltd | Wholesale & retail | 2022 |
| Acer Surgical Ltd | Health & social care | 2023 |
| ACH Properties Limited | Real estate | 2013 |
| Achieve and Partners Limited | Education | 2016 |
| Achieve Consultancy and Training Ltd. | Education | 2015 |
| Achughes Limited | Transport & logistics | 2025 |
| Acidale Limited | Hospitality | 2006 |
| ACJ Rail Engineering Ltd | Construction | 2024 |
| ACK York Ltd | Real estate | 2023 |
| Ackerley Agri Ltd | Agriculture & fishing | 2026 |
| Ackhorne 2026 Limited | Hospitality | 2026 |
| Ackton Pastures(Castleford) Management Company Limited | Real estate | 2015 |
| ACM Global Central Laboratory Limited | Professional & scientific | 1999 |
| ACM Global Central Laboratory Operations Limited | Professional & scientific | 2009 |
| ACN Groundworks Ltd | Construction | 2019 |
| ACN Ventures Ltd | Administrative & support | 2013 |
| Acollective Ltd | Real estate | 2015 |
| Acomb Bouncy Castles & Cleaning Limited | Other services | 2016 |
| Acomb Carers Ltd | Health & social care | 2022 |
| Acomb Chiropractic Clinic Limited | Health & social care | 2010 |
| Acomb Investments Yorkshire Limited | Real estate | 2010 |
| Acomb Medical Limited | Health & social care | 2012 |
| Acomb OUT of School Club Limited | Education | 2004 |
| Acomb Pressure Washing Ltd | Administrative & support | 2022 |
| Acomb Scheduling & Consultancy Ltd | Professional & scientific | 2025 |
| Acomb Shop Ltd | Wholesale & retail | 2025 |
| Acorn Assessors Limited | Financial services | 1998 |
| Acorn Community Recycling Limited | Wholesale & retail | 2018 |
| Acorn Editorial Limited | Professional & scientific | 2003 |
| Acousticabs Industrial Noise Control Limited | Construction | 1982 |
| Acquire Mining Limited | Professional & scientific | 2023 |
| Acquire Semiconductor Limited | Administrative & support | 2024 |
| Acra Services Ltd | Administrative & support | 2025 |
| Acro Recruitment Limited | Construction | 2019 |
| ACS Business Services Limited | Information & communication | 2024 |
| ACT 2 Transform Ltd | Professional & scientific | 2016 |
| ACT Housing Limited | Administrative & support | 2016 |
| ACT HR Services & Consultancy Ltd | Administrative & support | 2023 |
| ACT Refurbishments Ltd | Construction | 2025 |
| ACT Safety Ltd | Professional & scientific | 2022 |
| ACT York Limited | Real estate | 2018 |
| Action Printers Ltd | Information & communication | 2008 |
| ACTIV8 Camps Ltd | Health & social care | 2024 |
| ACTIV8 Coaching Limited | Education | 2016 |
| ACTIV8 Education Ltd | Education | 2024 |
| Active Aware Engaged Psychology Therapy and Consultancy Services Limited | Other services | 2022 |
| Active Device Development Limited | Professional & scientific | 2010 |
| Active Electrical Solutions (York) Ltd | Energy | 2009 |
| Active Transducer Research Limited | Manufacturing | 2017 |
| Acton Barnsley Limited | Professional & scientific | 2016 |
| Acton Pubs Ltd | Hospitality | 2026 |
| Actpr Ltd | Administrative & support | 2009 |