| Abira Food Ltd | Hospitality | 2018 |
| ABL Software Development Ltd | Professional & scientific | 2019 |
| Able Accountancy Limited | Professional & scientific | 2013 |
| Able Electrical Contracts Limited | Extraterritorial | 2005 |
| Able Electrical Inspection Limited | Construction | 1995 |
| Able Hygiene & Maintenance Limited | Administrative & support | 2003 |
| Abney Mews Management Company Limited | Households | 2012 |
| Above & Beyond Event Management Limited | Administrative & support | 2006 |
| ABP Empires Ltd | Real estate | 2023 |
| Abraxas Marketing Ltd | Professional & scientific | 2017 |
| Abseiling Ltd | Construction | 2026 |
| Absentia (1962) Ltd | Professional & scientific | 2013 |
| Absolute Data Services Limited | Wholesale & retail | 1998 |
| Absolute Frames Limited | Manufacturing | 2020 |
| Absolute Furniture Spraying Ltd | Construction | 2021 |
| Absolute Kitchen & Bathroom Ltd | Construction | 2023 |
| Absolute Recruiting Ltd | Administrative & support | 2016 |
| Absolute RPE Solutions Ltd | Health & social care | 2017 |
| Abtech Heating Limited | Construction | 1997 |
| Abvar Limited | Construction | 2012 |
| AC Finance Consulting Ltd | Information & communication | 2026 |
| AC Perera Consulting Ltd | Professional & scientific | 2025 |
| Academia Limited | Information & communication | 2003 |
| ACB2316 Ltd | Transport & logistics | 2024 |
| ACC Expert Services Ltd | Construction | 2021 |
| ACC Skyline Ltd | Transport & logistics | 2021 |
| Accentuate Hair & Beauty Group Ltd | Other services | 2025 |
| Access to Living Ltd | Education | 2009 |
| Accord Care Ltd | Professional & scientific | 2026 |
| Accord Living Developments Ltd | Financial services | 2026 |
| Accounts & Tax Store Limited | Professional & scientific | 2003 |
| ACD Podiatry Ltd | Health & social care | 2012 |
| Ace Savant Records Ltd | Information & communication | 2021 |
| Ace Stone Workers Ltd | Construction | 2019 |
| Ace Valet Ltd | Administrative & support | 2024 |
| ACJ Logistics Limited | Transport & logistics | 2015 |
| Acolyte Solutions Limited | Information & communication | 2014 |
| Acorn Project Management Services Limited | Professional & scientific | 2019 |
| Acoustical Investigation & Research Organisation Limited | Professional & scientific | 1958 |
| Acrelec International Development Limited | Information & communication | 2015 |
| Acrelec UK Limited | Information & communication | 2010 |
| Acro Cheer Ltd | Education | 2024 |
| Acro Food Limited | Wholesale & retail | 2023 |
| Acrobat Training and Consulting Limited | Information & communication | 2024 |
| Acrotrend Solutions Limited | Information & communication | 2007 |
| ACS Datacoms Ltd | Information & communication | 2018 |
| ACT Star Ltd | Transport & logistics | 2023 |
| Activate Skills Training Ltd | Education | 2024 |
| Active Heating & Renewables Ltd | Construction | 2009 |
| Active With Alexandra Ltd | Other services | 2021 |
| Actors Guild of UK Nollywood Limited | Other services | 2015 |
| Acttron Limited | Wholesale & retail | 1995 |
| Actum Advisory Ltd | Information & communication | 2026 |
| Adam Haulage Limited | Transport & logistics | 2023 |
| Adam Matthews Electrical Ltd | Construction | 2017 |
| Adam Turner Management Limited | Financial services | 2013 |
| Adams Roofing Ltd | Construction | 2015 |
| Adapting Capital Ltd | Administrative & support | 2022 |
| ADD Property Hub Ltd | Real estate | 2021 |
| Addcharge Energy Ltd | Construction | 2026 |
| Addcharge Ltd | Construction | 2021 |
| Addiscombe Road Ltd. | Administrative & support | 2026 |
| Addisonwoods Ltd | Extraterritorial | 2024 |
| Addlife Financial Ltd | Financial services | 2020 |
| Adele Anthony Property Ltd | Real estate | 2020 |
| Adem Traders Ltd | Administrative & support | 2020 |
| Adencast Limited | Administrative & support | 2023 |
| Adeyfield Eyecare Limited | Wholesale & retail | 2003 |
| ADI Haulage Ltd | Transport & logistics | 2018 |
| Adib Construction Ltd | Construction | 2026 |
| ADK Consulting Ltd | Professional & scientific | 2006 |
| ADK Digital Limited | Wholesale & retail | 2015 |
| ADL United Cargo Ltd | Transport & logistics | 2026 |
| Adlite Ltd | Information & communication | 2019 |
| Admedicus Limited | Health & social care | 2015 |
| Admin Transport Services Limited | | 1987 |
| Adpq Limited | Mining & quarrying | 2023 |
| ADR Property Services Ltd | Real estate | 2025 |
| Adrian Construct Ltd | Construction | 2012 |
| Adrian Holding Group Ltd | Real estate | 2026 |
| Adrian Structures Ltd | Construction | 2026 |
| Adroit Logic Ltd | Information & communication | 2015 |
| ADS Electrical Services (London) Limited | Construction | 2015 |
| Adsisda Ltd | Information & communication | 2024 |
| ADT INNOV8 Ltd | Construction | 2025 |
| Advance Player Development 2018 Ltd | Arts & recreation | 2018 |
| Advance Schemes Limited | Financial services | 2012 |
| Advanced Technical Panels Limited | Wholesale & retail | 1983 |
| Advantage NOW Limited | Administrative & support | 2011 |
| Adviseinc Ltd | Information & communication | 2014 |
| Adyanth Technologies Ltd | Information & communication | 2025 |
| Ae&An Ghionoiu Ltd | Construction | 2026 |
| Aedrus Ltd | Manufacturing | 2026 |
| Aelec Ltd | Construction | 2013 |
| AEO Educators Ltd | Education | 2020 |
| Aerotest Limited | Transport & logistics | 1990 |
| Aerotrace Limited | Administrative & support | 2025 |
| Aesthetic Solutions by Anita Ltd | Other services | 2022 |
| Aestheticsby-Jo-B Ltd | Other services | 2022 |
| Aether Management Ltd | Real estate | 2024 |