| Abco Enterprises Limited | Construction | 1983 |
| Abco Software Limited | Information & communication | 1997 |
| ABD Property Holdings Ltd | Real estate | 2024 |
| Abde Group Ltd | Wholesale & retail | 2024 |
| Abdullahi Abdullahi Company Ltd | Health & social care | 2020 |
| Abdullatif & Sons Ltd | Wholesale & retail | 2026 |
| ABE Motor Works Ltd | Wholesale & retail | 2018 |
| Abengoa Concessions Investments Limited | Energy | 2013 |
| Aberarder Wind Farm LLP | | 2015 |
| Abernedd Power Company Limited | Professional & scientific | 2007 |
| Aberta Ltd | Information & communication | 2007 |
| Abess Holdings Limited | Financial services | 2018 |
| ABG Real Estate Ltd | Real estate | 2021 |
| ABI Eastwell Ltd | Information & communication | 2017 |
| ABI Evans Design Ltd | Professional & scientific | 2022 |
| ABILITY2ACCESS | Construction | 1999 |
| Abingdon NO.1 Leasing Partnership LP | | 2008 |
| Abinger Investments Limited | Extraterritorial | 2016 |
| Abira Consulting Services Ltd | Professional & scientific | 2011 |
| Abiron Gourmet Limited | Administrative & support | 2024 |
| Abitop Consultants Ltd | Administrative & support | 2016 |
| ABL Homes Ltd | Real estate | 2025 |
| Able Instruments and Controls Limited | Wholesale & retail | 1984 |
| Able Journeys Ltd | Professional & scientific | 2012 |
| Able Projects Limited | Professional & scientific | 2014 |
| Able Trustees Limited | Administrative & support | 2020 |
| ABM Accountants Reading Ltd | Professional & scientific | 2014 |
| Abodi Estates Limited | Real estate | 2015 |
| Abose Engineering Ltd | Professional & scientific | 2024 |
| About Colour Limited | Other services | 2015 |
| About Homes Limited | Real estate | 2020 |
| About Sunday Ltd | Wholesale & retail | 2026 |
| Above & Beyond Experiences Ltd | Health & social care | 2021 |
| Above and Below Plumbing Services Limited | Construction | 2013 |
| Above the Bar Consultants Limited | Professional & scientific | 2022 |
| Abovo Holdings Ltd | Real estate | 2019 |
| ABR Health and Social Care Services Ltd | Health & social care | 2019 |
| Abraham Beckman Solution Ltd | Wholesale & retail | 2025 |
| Abrahams Building Investments Limited | Real estate | 2004 |
| Abrahams Building INVESTMENTS1 Limited | Real estate | 2026 |
| Abrahams Management Services Limited | Real estate | 2014 |
| Abrahamsharon Properties Limited | Real estate | 2026 |
| Abrar Zahin Ltd | Wholesale & retail | 2025 |
| Abril Learning & Technologies Ltd | Information & communication | 2025 |
| ABS Automation Systems Limited | Information & communication | 2018 |
| ABS Gurkha Ltd | Hospitality | 2012 |
| ABS UK Enterprises Ltd | Hospitality | 2026 |
| Absolute Digital Limited | Information & communication | 2002 |
| Absolute Dynamics Limited | Information & communication | 2017 |
| Absolute Equestrian Collective Ltd | Wholesale & retail | 2025 |
| Absolute Horizons Ltd | Professional & scientific | 2016 |
| Absolute INK Tattooing Ltd | Other services | 2011 |
| Absolutely Anything (Berkshire) Ltd | Construction | 2021 |
| Absolutely Fabulous Ltd | Other services | 2007 |
| ABT News Limited | Wholesale & retail | 2023 |
| Abundance Always Limited | Real estate | 2019 |
| Abundant Referrals Berkshire Ltd | Other services | 2026 |
| Abundant Referrals Ltd | Other services | 2012 |
| Abundantly Blessed Ltd | Public administration | 2022 |
| ABY Limited | Construction | 2016 |
| Ab’S Cabs Limited | Transport & logistics | 2025 |
| AC Compressors Limited | Energy | 2014 |
| AC London Limited | Wholesale & retail | 2025 |
| AC Plumbing and Heating Services Ltd | Construction | 2023 |
| AC Response Ltd | Administrative & support | 2020 |
| AC Restoration Services Limited | Wholesale & retail | 2014 |
| AC Vent-System Ltd | Construction | 2022 |
| Acacia Global Health Consulting Limited | Professional & scientific | 2023 |
| Acacia Natural Resource Consultants Limited | Professional & scientific | 2009 |
| Acacia Property Services Ltd | Construction | 2025 |
| Academic Conferences and Publishing International Ltd | Education | 2022 |
| Academic Estates Limited | Real estate | 2021 |
| Academic Journals International Ltd | Information & communication | 2026 |
| Academically Gifted Ltd | Wholesale & retail | 2019 |
| Academy Catering Limited | Hospitality | 1992 |
| Academy Furniture Hire Limited | Administrative & support | 2010 |
| Academy Insurance Services Limited | Financial services | 1995 |
| Academy Software Products Ltd | Extraterritorial | 2009 |
| Academy Windows Ltd | Extraterritorial | 2007 |
| Acadustri Limited | Professional & scientific | 2006 |
| ACB Driving School Ltd | Education | 2023 |
| ACC Management Ltd | Administrative & support | 2023 |
| ACC Online Limited | Wholesale & retail | 2022 |
| Accellacare UK Limited | Health & social care | 2000 |
| Access & Abbey Group Ltd | Construction | 2022 |
| Access K-Pop Ltd | Education | 2025 |
| Access Limited | Manufacturing | 1984 |
| Access Properties (Hampshire) Limited | Real estate | 2020 |
| Access-Ability Communications Technology | Education | 2005 |
| Accession Healthcare Consulting Limited | Professional & scientific | 2011 |
| Accomodo Enterprise Ltd | Administrative & support | 2021 |
| Accon UK Limited | Professional & scientific | 2007 |
| Accor Homes Ltd | Real estate | 2024 |
| Accordo Partners Limited | Professional & scientific | 2012 |
| Account Assistant Services Ltd | Information & communication | 2018 |
| Accountancy Online Limited | Professional & scientific | 2017 |
| Accountants Toolbox Ltd | Information & communication | 2024 |
| Accounting & Book-Keeping Consultants Limited | Professional & scientific | 2017 |
| Accounting Cloud Limited | Professional & scientific | 2024 |
| Accounting for VAT Limited | Professional & scientific | 1995 |