| Ace 24 Healthcare Ltd | Hospitality | 2014 |
| Ace 24 International Ltd | Health & social care | 2019 |
| Ace Consumables Ltd | Wholesale & retail | 2023 |
| Ace Green Energy UK Ltd | Energy | 2021 |
| Ace Heating & Cooling Services Ltd | Energy | 2019 |
| Ace J Properties Ltd | Real estate | 2025 |
| Ace Pave and Groundworks Limited | Construction | 2011 |
| Acecademy Ltd | Professional & scientific | 2025 |
| Aceitc Limited | Professional & scientific | 2023 |
| Acer Close (Frogmore) Management Company Limited | Households | 2024 |
| Acerbis Therapy Ltd | Health & social care | 2025 |
| Aces (Adams Computer & Electronic Services) Limited | Manufacturing | 1996 |
| Acess Ventures Limited | Financial services | 2026 |
| Acey Holdings Ltd | Financial services | 2018 |
| ACG Plant and Equipment Ltd | Administrative & support | 2026 |
| Achnacone Holdings Limited | Professional & scientific | 2026 |
| ACL Contract Solutions Ltd | Professional & scientific | 2025 |
| Acland Court Management Company Limited | Real estate | 1973 |
| Acland House Management Company Limited | Households | 2018 |
| ACM Services (Essex) Limited | Other services | 2007 |
| ACM Worldwide Ltd | Transport & logistics | 2025 |
| Acon Construction Group Limited | Construction | 2023 |
| Acon Trades Ltd | Construction | 2017 |
| Acorn Autism Specialists Limited | Health & social care | 2021 |
| Acorn Business Management Services Ltd | Professional & scientific | 2021 |
| Acorn Laboratory Limited | Health & social care | 2003 |
| Acorn Lodge Properties Limited | Construction | 2017 |
| Acorn Music (Essex) Limited | Education | 2011 |
| Acorngain Property Management Company Limited | Real estate | 1991 |
| ACP (Billericay) Limited | Real estate | 2022 |
| ACP Assessments and Consultancy Ltd | Health & social care | 2025 |
| ACP Commercial Investments Limited | Real estate | 2011 |
| ACP Transport Services Ltd | Transport & logistics | 2022 |
| Acquaintances&Colleagues Health Ltd | Health & social care | 2014 |
| Acropolis Greek Gyros Ltd | Hospitality | 2024 |
| Acrystone LLP | | 2011 |
| ACS Property Solutions Limited | Construction | 2023 |
| ACT One Training Services Ltd | Administrative & support | 2018 |
| ACT Services & Repairs Ltd | Manufacturing | 2021 |
| Actdrive Technology Limited | Information & communication | 2000 |
| Action Against Food Poverty CIC | Health & social care | 2026 |
| Actionworks UK Ltd | Professional & scientific | 2007 |
| Active Green Technology Ltd | Construction | 2019 |
| Active Planning Leads Ltd | Information & communication | 2020 |
| Active Products (UK) Limited | Administrative & support | 2003 |
| Active Sports Direction Limited | Manufacturing | 2010 |
| Activus Habitat Services Ltd | Agriculture & fishing | 2026 |
| Acton Vehicle Estimates Limited | Wholesale & retail | 2025 |
| Actronics Limited | Wholesale & retail | 2009 |
| Acts Consulting Limited | Professional & scientific | 2014 |
| Actualise Design Ltd | Administrative & support | 2012 |
| Actualwork Limited | Real estate | 1992 |
| Acuity Counselling Ltd | Health & social care | 2024 |
| Acura Properties Ltd | Real estate | 2018 |
| Acuregen Limited | Education | 2010 |
| AD Bradley Music Limited | Administrative & support | 2005 |
| AD Business Recovery Limited | Administrative & support | 2003 |
| AD Precision Services Ltd | Construction | 2018 |
| Ad-Purely Ltd | Wholesale & retail | 2025 |
| Adajov Care Solutions Ltd | Health & social care | 2017 |
| Adakeg Limited | Real estate | 2015 |
| Adam Adams Consulting Ltd | Professional & scientific | 2023 |
| Adam Brinkley Carpentry Limited | Administrative & support | 2007 |
| Adam Povey Investments Ltd | Administrative & support | 2025 |
| Adam Povey Properties Ltd | Real estate | 2017 |
| Adam Roberts Ltd | Information & communication | 2026 |
| Adam Roxby Ltd | Administrative & support | 2025 |
| Adam Wilce Limited | Construction | 2019 |
| Adam.Nvq Limited | Education | 2017 |
| Adamexpo Limited | Wholesale & retail | 2024 |
| Adams Publishing Limited | Information & communication | 2010 |
| Adamski Building Contractor Ltd | Construction | 2017 |
| Adaptive Athletics Limited | Manufacturing | 2025 |
| Adauxi Limited | Professional & scientific | 2011 |
| Adauxi Services Limited | Professional & scientific | 2023 |
| ADC Brickwork Ltd | Construction | 2021 |
| ADC Tiling Ltd | Construction | 2021 |
| Addept Group Limited | Financial services | 2024 |
| Addisand Limited | Hospitality | 2003 |
| Additions Hair Salon Limited | Other services | 2023 |
| Adds Room Lofts Ltd | Construction | 2021 |
| ADE Protection Ltd | Administrative & support | 2019 |
| Adelante Asset Holdings Limited | Administrative & support | 2009 |
| Adelante Asset Management Limited | Financial services | 2003 |
| Adelco Ltd | Real estate | 2017 |
| Adele Waters Wealth Management Ltd | Professional & scientific | 2021 |
| Adelfi Ltd | Other services | 2014 |
| Adept Construction East Anglia Ltd | Professional & scientific | 2018 |
| Adept Wealth Management Limited | Financial services | 2018 |
| Adia PR Ltd | Professional & scientific | 2013 |
| Adima Limited | Financial services | 2025 |
| Adira Estates Ltd | Real estate | 2023 |
| Adjosa Limited | Hospitality | 2017 |
| ADL Electrical (UK) Limited | Manufacturing | 2020 |
| ADL Heating and Cooling Solutions Ltd | Energy | 2022 |
| Adlf Limited | Information & communication | 2013 |
| Adlink Media Limited | Professional & scientific | 2010 |
| Admin Inc Ltd | Administrative & support | 2017 |
| Admirals Green (Management Company) Limited | Real estate | 2020 |
| Admor Properties Limited | Real estate | 2023 |