| Abbots Ride Land Limited | Real estate | 2006 |
| ABC Collective Ltd | Wholesale & retail | 2023 |
| ABC Holdings Group Limited | Financial services | 2025 |
| ABC Property Investments Limited | Real estate | 2012 |
| Abclivein Care Limited | Public administration | 2018 |
| Abed Properties Limited | Hospitality | 2013 |
| Abenouchi Limited | Real estate | 2021 |
| Aberdour Advisers Limited | Professional & scientific | 2004 |
| Aberdour Properties Limited | Professional & scientific | 2010 |
| ABH Cross Ltd | Real estate | 2025 |
| Abigail Burch Ltd | Professional & scientific | 2015 |
| Abildgaard Landscaping Contractors Limited | Construction | 2005 |
| Abimonel Ltd | Wholesale & retail | 2018 |
| Abmet Ltd | Health & social care | 2015 |
| Abode Architects LLP | | 2004 |
| Abode Solutions Limited | Construction | 2014 |
| Above and Beyond Funerals Ltd | Other services | 2019 |
| Abromley Ltd | Real estate | 2025 |
| Absolute Signs Ltd | Manufacturing | 2011 |
| Absolute Smart Repairs Ltd | Wholesale & retail | 2025 |
| AC Decorators South Limited | Construction | 2026 |
| Acacia Environmental Ltd | Professional & scientific | 2020 |
| Acamar Coaching Limited | Professional & scientific | 2003 |
| Access for Hire Limited | Administrative & support | 2017 |
| Accor Services Limited | Real estate | 2017 |
| Accord Surveyors Ltd | Professional & scientific | 2009 |
| Account Carbon Ltd | Professional & scientific | 2025 |
| Accounting Contact Ltd | Professional & scientific | 2013 |
| Ace of Spades Landscape & Maintenance Ltd | Administrative & support | 2017 |
| Ace Stock Limited | Professional & scientific | 2002 |
| Ace Tanks Ltd | Construction | 2020 |
| Ace UK (Tanks) Ltd | Extraterritorial | 2022 |
| Acer Tree Services Ltd. | Administrative & support | 2019 |
| Aces High Limited | Professional & scientific | 1979 |
| Achiive Limited | Education | 2005 |
| ACJ Electrical Installations Limited | Construction | 2015 |
| Acmh Consulting Limited | Professional & scientific | 2023 |
| Acmh Freight Forwarding Limited | Transport & logistics | 2025 |
| Acorn Actives Ltd | Extraterritorial | 2020 |
| Acorn Office Solutions Limited | Administrative & support | 2005 |
| Acorn Packaging Products Limited | Wholesale & retail | 2009 |
| Across Business Psychology Limited | Health & social care | 2008 |
| ACT 5 Arts Ltd | Arts & recreation | 2026 |
| Actors Station Ltd | Arts & recreation | 2021 |
| Adam Brown Media Ltd | Information & communication | 2025 |
| Adam Doven Construction Limited | Construction | 2014 |
| Adapt Architecture Limited | Real estate | 2010 |
| Adatis Group Limited | Financial services | 2019 |
| ADB Stage and Studio Lighting Limited | Extraterritorial | 1991 |
| Adbond Packaging Consulting Ltd | Professional & scientific | 2017 |
| ADC Consultants Ltd | Information & communication | 2025 |
| Adcel Ltd | Professional & scientific | 2013 |
| Addcom IT Limited | Information & communication | 2008 |
| Addlestead Consulting Limited | Professional & scientific | 2015 |
| Adelinerecruits Ltd | Real estate | 2019 |
| Adept Communications Systems Ltd | Information & communication | 2012 |
| Adlar Ltd | Construction | 2023 |
| Adlår Group Limited | Construction | 2024 |
| Admatrix Limited | Professional & scientific | 2013 |
| Adraga Consulting Limited | Professional & scientific | 2022 |
| Adret Holdings Limited | Professional & scientific | 2026 |
| Adroit Engineering Solutions Ltd | Professional & scientific | 2022 |
| Adsign Advertising Limited | Administrative & support | 1993 |
| Adsign Limited | Manufacturing | 1998 |
| Advanced Garden Fencing Limited | Administrative & support | 2005 |
| Advanced Mathematical Software Limited | Extraterritorial | 1978 |
| Adventures and Awards Ltd | Wholesale & retail | 2023 |
| AEB Construction Limited | Construction | 2017 |
| Aegis Interior Design Limited | Professional & scientific | 2010 |
| Aegis Property Solutions Ltd | Real estate | 2004 |
| Aerials 4 YOU Surrey Ltd | Wholesale & retail | 2014 |
| Aerospace Coatings Limited | Administrative & support | 1991 |
| AES Sidhe Ltd | Construction | 2014 |
| Aesthetic Homes Group Limited | Financial services | 2015 |
| Aesthetic Properties Holdings Ltd | Real estate | 2018 |
| Aesthetic Work OUT Ltd | Arts & recreation | 2021 |
| Affection Limited | Wholesale & retail | 2020 |
| Agar Properties Limited | Real estate | 2016 |
| Agdd Limited | Professional & scientific | 2020 |
| Agenda (UK) Limited | Manufacturing | 2006 |
| Ages (UK) Ltd | Professional & scientific | 2009 |
| AGM Portfolio Limited | Real estate | 2026 |
| AGM Studio Ltd | Real estate | 2025 |
| Agriculture Trading Systems Ltd | Information & communication | 2023 |
| Aham Foods Limited | Hospitality | 2023 |
| AI2EV Limited | Information & communication | 2018 |
| Aidan Mcevoy Ltd | Manufacturing | 2014 |
| Aide-Memoire Publications Limited | Information & communication | 2020 |
| Aiding Learning & Instruction Ltd | Education | 2019 |
| Aigtm Limited | Professional & scientific | 2024 |
| Ailias AI Ltd | Information & communication | 2025 |
| AIM Audio Visual Ltd | Other services | 2017 |
| AIM High FC Ltd | Education | 2023 |
| Aims Achieved Ltd | Professional & scientific | 2019 |
| Aion Farm Ltd | Agriculture & fishing | 2025 |
| Air Cover PR Limited | Professional & scientific | 2020 |
| Aireye Ltd | Manufacturing | 2014 |
| Airnesco Group Holdings Limited | Financial services | 2025 |
| Airworthy Limited | Professional & scientific | 1980 |
| Airworthy Trustees Limited | Professional & scientific | 2017 |