| Ace Tyres Commercial Ltd | Wholesale & retail | 2016 |
| Ace Underpinning Limited | Construction | 2003 |
| Acelroy Limited | Administrative & support | 2024 |
| Acemoirai Ltd | Wholesale & retail | 2025 |
| Acer Defense Ltd | Professional & scientific | 2025 |
| Achu Real Estate UK Ltd | Real estate | 2024 |
| Acid Colour Ltd | Information & communication | 2026 |
| Acis Ventures (UK) Ltd | Financial services | 2026 |
| Ackroyds Autos Ltd | Wholesale & retail | 2024 |
| ACM Advisory Group Limited | Professional & scientific | 2026 |
| Acmg Trading Ltd | Wholesale & retail | 2020 |
| Acoa Flint Limited | Real estate | 2026 |
| Acomet Company Limited | Professional & scientific | 2005 |
| Acorns and Oaks Limited | Administrative & support | 2021 |
| Acqodd Ltd | Information & communication | 2024 |
| Acquisitions and Development Ltd | Real estate | 2011 |
| Acrobond Limited | Real estate | 1976 |
| Act-Put Limited | Manufacturing | 2017 |
| Action Business Builder Limited | Health & social care | 2008 |
| Actioninclusion Ltd | Professional & scientific | 2024 |
| Actium Occasions Limited | Other services | 2019 |
| Active Investments (Kent) Ltd | Real estate | 2021 |
| Active Learning Academy Ltd | Education | 2018 |
| Active Retail (UK) Limited | Wholesale & retail | 2007 |
| Actuarial Guru Ltd | Financial services | 2011 |
| Acubeproductions Ltd | Information & communication | 2024 |
| AD Holdings London Ltd | Real estate | 2025 |
| ADA OIL and GAS Services Ltd | Mining & quarrying | 2022 |
| Adam Hedges Golf Limited | Education | 2024 |
| Adams Haulage Ltd | Transport & logistics | 2025 |
| Adamsky Motors Ltd | Wholesale & retail | 2026 |
| Adana Cleaning Ltd | Administrative & support | 2018 |
| Adapa Advisory Limited | Professional & scientific | 2019 |
| Adbe Financial Limited | Professional & scientific | 2018 |
| Adcav Limited | Information & communication | 2011 |
| Addair Holdings Limited | Financial services | 2020 |
| Addair Services Limited | Construction | 2020 |
| Addwings Travel & Image Limited | Professional & scientific | 2025 |
| Adelaide Court Management Limited | Households | 1970 |
| Adeo South East Limited | Real estate | 2013 |
| Aderopo Healthcare Ltd | Health & social care | 2022 |
| Aderopo Limited | Public administration | 2025 |
| Ades Driving School Ltd | Education | 2022 |
| ADF Pricing Solutions Limited | Financial services | 2014 |
| Adhi Sakthi Advance Systems Ltd | Information & communication | 2019 |
| ADL Projects (London) Ltd | Administrative & support | 2014 |
| Adlab MED Ltd | Health & social care | 2012 |
| Admt Business Solutions Limited | Administrative & support | 2021 |
| Adoy Ltd | Arts & recreation | 2025 |
| ADP Compliance Ltd | Public administration | 2024 |
| Adrian Perks Limited | Administrative & support | 2016 |
| Adrian Tataru Ltd | Construction | 2026 |
| Adriatic Consulting Limited | Professional & scientific | 2016 |
| ADS Build 1 Ltd | Construction | 2022 |
| ADS Build Ltd | Construction | 2011 |
| ADS Builders Kent Ltd | Construction | 2022 |
| ADS on Top Ltd | Professional & scientific | 2014 |
| Advance Electrical Services Ltd | Construction | 2020 |
| Advanced Global Technology Management Ltd | Professional & scientific | 2016 |
| Advaya Solutions Ltd | Health & social care | 2024 |
| Adved Infotech Limited | Professional & scientific | 2023 |
| Advent AGE Limited | Professional & scientific | 2008 |
| Adwell Environmental Limited | Administrative & support | 1998 |
| AEC Boxing Ltd | Arts & recreation | 2026 |
| AEC Technology UK Limited | Administrative & support | 2026 |
| AEG Solutions Limited | Professional & scientific | 2016 |
| Aegis Commodities (UK) Limited | Wholesale & retail | 2016 |
| Aegis Defence Group Ltd | Professional & scientific | 2025 |
| AEH Property Investments Ltd | Real estate | 2025 |
| Aero Sports Protection Limited | Wholesale & retail | 2009 |
| Aesthetify Ltd | Other services | 2023 |
| Aetherian Properties Ltd | Real estate | 2025 |
| Aeun Limited | Manufacturing | 2015 |
| AF Silver Limited | Administrative & support | 2024 |
| Affinity Software Limited | Information & communication | 2023 |
| Affinity Systems & Development Limited | Information & communication | 1998 |
| Affinity Talent Group Ltd | Information & communication | 2019 |
| Affordable Quality Care Ltd | Health & social care | 2025 |
| African Inside Ltd | Wholesale & retail | 2022 |
| Afrizone Capital Limited | Financial services | 2021 |
| Ag&M Limited | Arts & recreation | 2012 |
| AGC Baron Property Limited | Real estate | 2026 |
| AGD Taxis Ltd | Transport & logistics | 2021 |
| Agdo Healthcare Ltd | Health & social care | 2021 |
| AGE Concern Orpington and District | Health & social care | 2011 |
| Agile Computers Limited | Information & communication | 1992 |
| Agile Culture Limited | Professional & scientific | 2017 |
| Agiso Ltd | Administrative & support | 2019 |
| AGK Electrical Ltd | Construction | 2020 |
| Agne Construction Ltd | Construction | 2025 |
| Agora Properties Ltd | Professional & scientific | 2016 |
| Agra Fitness Limited | Arts & recreation | 2024 |
| Agra Properties Limited | Real estate | 2023 |
| Agredos Ltd | Real estate | 2024 |
| Agronic Global Limited | Wholesale & retail | 2018 |
| AGS Cleaning Limited | Other services | 2017 |
| Aguba Property Partners Ltd | Real estate | 2022 |
| Aguba Ventures Ltd | Financial services | 2024 |
| AGW Building Services Limited | Construction | 2025 |
| Ahsen Boutique Limited | Wholesale & retail | 2023 |