| A-Grade Roofing & Leadwork Limited | Construction | 2026 |
| A-Hard Builders Ltd | Manufacturing | 2021 |
| A.F.A. Limited | Financial services | 1982 |
| A.P Rigging Services Ltd | Construction | 2025 |
| A.R. Betteridge Limited | Financial services | 1973 |
| A.R.B. Property Projects Limited | Real estate | 2008 |
| A.W. Properties RTM Company Limited | Real estate | 2008 |
| A1 Barber (Sidcup) Limited | Other services | 2019 |
| A1 Barber Shop Sidcup Limited | Other services | 2026 |
| A1 Installations (London) Limited | Information & communication | 2006 |
| A11 Limited | Construction | 2023 |
| A2Z Vehicles Limited | Wholesale & retail | 2022 |
| A2ZI Property Group Limited | Real estate | 2019 |
| A6 Mots Limited | Administrative & support | 2012 |
| AA Postal Services Ltd | Wholesale & retail | 2024 |
| Aadept Environmental Limited | Administrative & support | 2003 |
| Aadept Properties Limited | Real estate | 2005 |
| AAG Fitness Limited | Other services | 2013 |
| AAM Retail Ltd | Wholesale & retail | 2023 |
| AAP Ground Maintenance Ltd | Administrative & support | 2016 |
| AAP Property Developments Limited | Real estate | 2021 |
| Aaron Drilling Services Limited | Construction | 2015 |
| Aasra Care Homes Limited | Health & social care | 2021 |
| Aasra Care Limited | Health & social care | 2021 |
| Aasra Group Limited | Financial services | 2025 |
| AB Brickwork and Building Services Limited | Construction | 2019 |
| AB Security Ltd | Administrative & support | 2019 |
| Abacus Aquatics Limited | Wholesale & retail | 2019 |
| Abalone Shell Limited | Wholesale & retail | 2025 |
| Abanoob Ltd | Health & social care | 2021 |
| ABB Distributions Ltd | Wholesale & retail | 2024 |
| Abbey Autos Centre Limited | Wholesale & retail | 2009 |
| Abbey Trading Estates Limited | Real estate | 2012 |
| Abby Properties Limited | Administrative & support | 2014 |
| ABC Home Buyers Ltd | Real estate | 2024 |
| ABC Hub Ltd | Hospitality | 2024 |
| ABC MOT Centre Limited | Wholesale & retail | 2025 |
| Abcm Limited | Health & social care | 2022 |
| Abdia Capital Limited | Administrative & support | 2023 |
| Abell Sttr Ltd | Professional & scientific | 2017 |
| ABI Roofing Limited | Administrative & support | 2016 |
| Ability MEP Ltd | Construction | 2021 |
| Able Control Solutions Limited | Professional & scientific | 2016 |
| ABM Creative Media Ltd | Information & communication | 2026 |
| Abode Electrical Services Limited | Construction | 2017 |
| Above Average Electrical Limited | Construction | 2022 |
| Absi Property Services Ltd | Real estate | 2025 |
| Absolute Access Services Limited | Construction | 2008 |
| Absolute Glazing Solutions Limited | Construction | 2016 |
| Absolute Scaffolding Incorporated Limited | Construction | 2023 |
| AC Excellence Limited | Real estate | 2010 |
| AC Training Ltd | Professional & scientific | 2018 |
| Ac-Com Networks Ltd | Information & communication | 2018 |
| Academiacare Ltd | Education | 2024 |
| Academic School of Management Limited | Education | 2025 |
| Acan Property Ltd | Real estate | 2020 |
| Accent Studio Limited | Professional & scientific | 2011 |
| Access Building and Property Maintenance Ltd | Construction | 2013 |
| Access College Ltd | Hospitality | 2009 |
| Accfinix Limited | Professional & scientific | 2025 |
| Accounting Solutions Kent Limited | Professional & scientific | 2024 |
| Accurate Heating Limited | Construction | 2015 |
| Ace Cleaning (London) Services Limited | Administrative & support | 2017 |
| Ace Frame Windows and Doors Ltd | Construction | 2026 |
| Ace Production Services Ltd | Professional & scientific | 2020 |
| Ace Tech Consulting Ltd | Construction | 2025 |
| Acell Communications Ltd | Administrative & support | 2020 |
| Acer Carpentry and Joinery Limited | Construction | 2024 |
| Acer Construction Services Limited | Professional & scientific | 2024 |
| Aces Brunch Ltd | Hospitality | 2024 |
| Aceyblocks Productions Limited | Construction | 2018 |
| Achaesthetics Ltd | Education | 2022 |
| ACJ Security Systems Ltd | Administrative & support | 2019 |
| ACM Building Surveys Limited | Administrative & support | 2010 |
| Acmr Holdings Limited | Financial services | 2021 |
| Acousticspace Ltd | Construction | 2026 |
| Active Care Connect Ltd | Public administration | 2026 |
| Active Community Kent Limited | Administrative & support | 2023 |
| Active Community NWK CIC | Arts & recreation | 2020 |
| Active Cooling UK Ltd | Construction | 2025 |
| Active Fire UK Ltd | Public administration | 2023 |
| Acton W3 Apartments Ltd | Hospitality | 2022 |
| Actorad Limited | Other services | 2013 |
| Acurium Ltd | Information & communication | 2025 |
| Acute Consulting Limited | Professional & scientific | 2019 |
| Acute Plumbing and Heating Limited | Construction | 2016 |
| AD Development Projects Limited | Extraterritorial | 2006 |
| AD Orthodontics Limited | Health & social care | 2015 |
| ADA Electrical Ltd | Construction | 2019 |
| Adage Credit | Information & communication | 2010 |
| Adage Systems IT Limited | Information & communication | 2002 |
| Adams Electrical Services (GOC) Limited | Manufacturing | 2019 |
| Addiction Release Limited | Health & social care | 2016 |
| Addington DRY Cleaners Limited | Other services | 2014 |
| Aditim Ltd | Wholesale & retail | 2021 |
| ADJ Creations Limited | Construction | 2017 |
| ADM Commissioning Services Limited | Administrative & support | 2019 |
| Admin Link Limited | Administrative & support | 2012 |
| Adnovate Clinical Development Strategies Ltd | Professional & scientific | 2014 |
| Adoma Constructions Ltd | Construction | 2018 |