| Abletriple Ltd | Professional & scientific | 1988 |
| Ablett Property Management Ltd | Real estate | 2024 |
| ABM Electrical Services Yorkshire Ltd | Construction | 2025 |
| ABM Estates Ltd | Real estate | 2016 |
| ABM Financial Management Limited | Financial services | 1999 |
| ABM Used Cars Ltd | Wholesale & retail | 2025 |
| ABN Investments Yorkshire Ltd | Real estate | 2021 |
| Abou Clinical Services Ltd | Health & social care | 2026 |
| Above & Beyond Therapy Aesthetics Limited | Other services | 2017 |
| Above Access Scaffolding Limited | Other services | 2009 |
| Above Investments Ltd | Real estate | 2019 |
| Above Limits Scaffolding Ltd | Construction | 2024 |
| Above the Below Ltd | Manufacturing | 2019 |
| ABR England Ltd | Health & social care | 2019 |
| ABR Healthcare Ltd | Health & social care | 2015 |
| ABR Investments Ltd | Real estate | 2024 |
| ABR Projects Limited | Construction | 2011 |
| Abraclean Limited | Manufacturing | 1978 |
| Abrahams Recovery & Repairs Limited | Wholesale & retail | 2023 |
| Abrantes Properties Limited | Health & social care | 2023 |
| Abrasives Online Ltd | Wholesale & retail | 2025 |
| Abraxis Ltd. | Hospitality | 2016 |
| Abrita LLP | | 2003 |
| Abroad Dreams Consultants Ltd | Administrative & support | 2025 |
| Abroad Estore Ltd | Wholesale & retail | 2026 |
| Abroad Pro Travels Ltd | Administrative & support | 2024 |
| ABS Metals and Waste Limited | Water & waste | 2008 |
| ABS Oral Surgery Limited | Health & social care | 2019 |
| Absb Drainage Limited | Water & waste | 2012 |
| Abseilute Access Limited | Construction | 2020 |
| Absent Cooks Limited | Hospitality | 2002 |
| Absheg Dynamic Resources Limited | Administrative & support | 2025 |
| Absolute Aquatics Limited | Administrative & support | 2020 |
| Absolute Fire Solutions Ltd | Construction | 2022 |
| Absolute Joinery Ltd | Construction | 2024 |
| Absolute Spine Limited | Health & social care | 2010 |
| Absolute Staircase Solutions Ltd | Construction | 2025 |
| Absolute-Mayhem Ltd | Arts & recreation | 2019 |
| Absoluteness Ltd | Other services | 2019 |
| Abss Fabrications Ltd | Manufacturing | 2015 |
| Abtala Limited | Transport & logistics | 2025 |
| Abtech Limited | Manufacturing | 2006 |
| ABU Dhabi Market Limited | Wholesale & retail | 2023 |
| Abukai Williams Limited | Health & social care | 2022 |
| Abyssinian Friends Association (AFA) | Other services | 2019 |
| AC Bathrooms & Heating Limited | Wholesale & retail | 2013 |
| AC Bell Medical Ltd | Health & social care | 2022 |
| AC Educational Psychology Ltd | Health & social care | 2024 |
| AC Professionals Ltd | Professional & scientific | 2020 |
| AC Tech Ltd | Information & communication | 2023 |
| AC Trade & Service Supply Ltd | Wholesale & retail | 2023 |
| Ac/Cf Design Limited | Professional & scientific | 1989 |
| ACA Windows Limited | Manufacturing | 2006 |
| Acacia Technology Limited | Information & communication | 2022 |
| Academic Progress Hub Ltd | Education | 2023 |
| Academy Cleaning Services (UK) Limited | Administrative & support | 2010 |
| Academy Construction Ltd | Construction | 2016 |
| Academy for International Migration Studies Ltd. | Information & communication | 2023 |
| Academy of Sustainable Finance, Accounting, Accountability & Governance (Asfaag) CIC | Professional & scientific | 2021 |
| Acahm&Co Limited | Other services | 2023 |
| Acai ME Ltd | Wholesale & retail | 2025 |
| Acantecs Limited | Manufacturing | 2022 |
| Acarna Limited | Information & communication | 2024 |
| Acaster Flockton Limited | Information & communication | 2022 |
| ACC Electrical Services (UK) Limited | Construction | 2014 |
| ACC Invest Ltd | Households | 2022 |
| Accelerate Lifestyle Limited | Wholesale & retail | 2006 |
| Accelerate Outcome Ltd | Information & communication | 2026 |
| Accelerate Performance Centre Limited | Health & social care | 2013 |
| Accelsales Limited | Professional & scientific | 2022 |
| ACCENDO360 Ltd | Administrative & support | 2021 |
| Acceptspec Limited | Professional & scientific | 1953 |
| Access Accommodation Ltd | Real estate | 2000 |
| Access ALL Areas Travel Limited | Transport & logistics | 2023 |
| Access and Adapt Ltd | Health & social care | 2013 |
| Access Commercial Investors 1 Limited | Financial services | 2015 |
| Access Commercial Lending Limited | Financial services | 2016 |
| Access Components Ltd | Wholesale & retail | 2023 |
| Access Credit Control Ltd | Financial services | 2011 |
| Access Credit Management Limited | Professional & scientific | 2000 |
| Access Engineering (North) Limited | Manufacturing | 1997 |
| Access Horizons Ltd | Other services | 2018 |
| Access Space Network | Information & communication | 2002 |
| Access Techniques Limited | Education | 2010 |
| Access Timber Products Ltd | Manufacturing | 2012 |
| Access to Growth GM Limited | Financial services | 2017 |
| Access to Investment GM Limited | Financial services | 2020 |
| Accessories Attic Limited | Wholesale & retail | 2017 |
| Accident Liability Investigations Limited | Administrative & support | 2012 |
| Accident Solicitors Direct Limited | Professional & scientific | 2008 |
| Accio Digital Ltd | Information & communication | 2018 |
| Accolade Medical Services Ltd | Health & social care | 2014 |
| ACCOMM4U Limited | Real estate | 2024 |
| Accountancy Tuition (Sheffield) Limited | Education | 1977 |
| Accounting and Office Management Ltd | Professional & scientific | 2017 |
| Accounting Know-How Limited | Professional & scientific | 2016 |
| Accounting on YOU Ltd | Professional & scientific | 2021 |
| Accounts and Tax Support Limited | Professional & scientific | 2026 |
| Accountsability (Sheffield) Limited | Professional & scientific | 2006 |
| Accufix Limited | Construction | 2003 |