| Ability Accounting Services Limited | Professional & scientific | 2002 |
| Ability First Limited | Information & communication | 2005 |
| Able Door Spring Company Ltd | Administrative & support | 2007 |
| Able Doors Limited | Administrative & support | 2007 |
| Able Enforcement & Security Services Ltd | Administrative & support | 2024 |
| Able Estimating Ltd | Professional & scientific | 2022 |
| Able to Cable Limited | Information & communication | 1990 |
| ABN Technet Ltd | Information & communication | 2022 |
| Aboai Ltd | Information & communication | 2026 |
| ABR Property Ltd | Real estate | 2018 |
| Abracadabra Teddy Bears Limited | Wholesale & retail | 2002 |
| Abridge Golf & Country Club Limited | Arts & recreation | 1962 |
| Abridge Golf Club (Holdings) Limited | Arts & recreation | 2001 |
| Abroad Wholesale Ltd | Wholesale & retail | 2026 |
| Absl Print Limited | Administrative & support | 2008 |
| Absolute Entrepreneur Ltd | Professional & scientific | 2010 |
| Absolutely Plumbing Limited | Construction | 2003 |
| Abui Distributions Ltd | Wholesale & retail | 2026 |
| Abundanceblueprints Ltd | Information & communication | 2023 |
| Abva Services Ltd | Professional & scientific | 1999 |
| Ac.Construct Ltd | Construction | 2024 |
| Acacia Business Services Limited | Professional & scientific | 2005 |
| Academy Aviation Limited | Education | 2018 |
| Academy Care Training Limited | Education | 2002 |
| Accelerate Productions / Events by Knight Limited | Arts & recreation | 2004 |
| Access & Lock Limited | Administrative & support | 2002 |
| Access Security Limited | Real estate | 1977 |
| Accident Claim Treatment Ltd | Information & communication | 2008 |
| Acclaim DMW Holdings Limited | Other services | 2016 |
| Accountancy Advisory Services Ltd | Professional & scientific | 2010 |
| Accountant on the NET Ltd | Professional & scientific | 2003 |
| Accountants T. R. South & Co Limited | Professional & scientific | 2003 |
| Accounts Center Associates Limited | Professional & scientific | 2004 |
| Accounts Center Limited | Financial services | 2001 |
| Accredisure Technical Services Limited | Professional & scientific | 2014 |
| Accredited Locksmith Services Limited | Administrative & support | 1997 |
| Accu Construction Solutions Ltd. | Construction | 2014 |
| Accurate Systems Limited | Information & communication | 1998 |
| Accurus Property Services Limited | Construction | 2003 |
| Ace Dent Holdings Limited | Extraterritorial | 1997 |
| Ace Design & Development Limited | Professional & scientific | 2004 |
| Ace Fencing Limited | | 1993 |
| Ace Revenues Ltd | Professional & scientific | 2007 |
| Acedent Limited | Wholesale & retail | 2002 |
| Acefarm Limited | Real estate | 1987 |
| Acelink Communications Limited | Wholesale & retail | 1994 |
| Acepine Builders Limited | | 1989 |
| Achlers Ltd | Wholesale & retail | 2024 |
| Acorn Mortgage Services (Essex) Limited | Financial services | 2006 |
| Acorn P C Limited | Wholesale & retail | 2007 |
| Acorn Packaging Services Limited | Transport & logistics | 1982 |
| Acorn Property Agents Ltd | Real estate | 2013 |
| Acorn Window Services Limited | Wholesale & retail | 2001 |
| Acowhite Limited | Manufacturing | 2025 |
| Acquiro Properties Ltd | Real estate | 2007 |
| Acrom Limited | Information & communication | 2004 |
| Active Electrical Solutions Limited | Construction | 2005 |
| Activeskills Recruitment Ltd | Other services | 2024 |
| Actlodge Limited | Other services | 2004 |
| Acuma Business Solutions Limited | Professional & scientific | 2005 |
| Acumen Lloyds Wharf Ltd | Real estate | 2024 |
| Acumen Real Estate Ltd | Real estate | 2022 |
| Acumen Realty Services Ltd | Professional & scientific | 2024 |
| Acute Healthcare Limited | Health & social care | 2007 |
| AD Infinitum Ltd | Professional & scientific | 2004 |
| AD Logistics Services Ltd | Transport & logistics | 2016 |
| AD World Ltd | Wholesale & retail | 2025 |
| ADA TR Limited | Hospitality | 2024 |
| Adam Electrical Limited | Construction | 2013 |
| Adam Taylor Plumbing & Heating Limited | Construction | 2003 |
| Adam Watches Ltd | Wholesale & retail | 2024 |
| Adamantium Group Ltd | Information & communication | 2006 |
| Adapt Concept Partitions Company Limited | Wholesale & retail | 2003 |
| Adas Calibration East London Ltd | Wholesale & retail | 2026 |
| Addison and Khan Solicitors London Limited | Professional & scientific | 2014 |
| Addison Construction Ltd | Construction | 2006 |
| Additions (Home Extensions) Limited | | 1985 |
| Addure Limited | Other services | 2020 |
| Addwell Systems Limited | Wholesale & retail | 1998 |
| Adeeo Ltd | Construction | 2019 |
| Adefag UK Ltd | Health & social care | 2022 |
| Adekhad Medical Services Limited | Health & social care | 2024 |
| Adept Editorial Ltd | Professional & scientific | 2007 |
| Adewole & Associates Ltd | Health & social care | 2024 |
| Adewole Properties Limited | Real estate | 2025 |
| Adhesive Technical Services Limited | Administrative & support | 2006 |
| Adisaan Ltd | Wholesale & retail | 2024 |
| Adissh Limited | Wholesale & retail | 2023 |
| ADK Productions Ltd | Arts & recreation | 2016 |
| ADL Interiors Limited | Construction | 2007 |
| Adland Print Group Limited | Manufacturing | 1989 |
| ADM Consultancy Solutions Limited | Wholesale & retail | 2016 |
| Admissions Unlocked Ltd | Education | 2025 |
| Admost Ltd | Wholesale & retail | 2004 |
| Adoptglen Limited | Professional & scientific | 1983 |
| Adore Beauty Rooms Ltd | Other services | 2024 |
| Adore Your Pelvic Floor Limited | Education | 2016 |
| Adorn Advertising Limited | Other services | 2002 |
| Adrg Ltd | Hospitality | 2019 |
| Adrian B & Sons Groundworks Limited | Construction | 2022 |