| Absolute Focus Limited | Information & communication | 2017 |
| Absolute Martial Arts Ashtead Ltd | Arts & recreation | 2025 |
| ABV Estate Ltd | Real estate | 2026 |
| AC Energy Solutions Limited | Construction | 2009 |
| Academic Education Consultancy Ltd | Other services | 2012 |
| Academy Management Company Limited | Households | 1982 |
| Academy of Systematic Kinesiology Limited(The) | Health & social care | 1987 |
| Accel Services Limited | Administrative & support | 2024 |
| Accelerant Events Ltd | Administrative & support | 2025 |
| Accelerate Property Limited | Real estate | 2023 |
| Access Advisors (UK) Limited | Professional & scientific | 2013 |
| Access Platforms (UK) Limited | Construction | 2009 |
| Access VFX Limited | Information & communication | 2018 |
| Accidentrepairs.Co.Uk Limited | Wholesale & retail | 2019 |
| Acclaim Estates Ltd | Real estate | 2024 |
| Accountally Limited | Professional & scientific | 2022 |
| Accounting Surrey Limited | Professional & scientific | 2014 |
| Accountingease Ltd | Professional & scientific | 2022 |
| Accsoftholding Ltd | Information & communication | 2025 |
| Ace Property Provisions CIC | Hospitality | 2023 |
| ACL Capital Limited | Professional & scientific | 2009 |
| Acornford Estates Limited | Construction | 1992 |
| Acre 570 Limited | Real estate | 2002 |
| Across Boundaries Consulting Ltd | Professional & scientific | 2025 |
| ACS Electrical Services Ltd | Construction | 2017 |
| ACS Three Limited | Wholesale & retail | 2021 |
| Active FOX Limited | Professional & scientific | 2015 |
| Active Sense Ltd | Professional & scientific | 2017 |
| Actros 74 Ltd | Health & social care | 2019 |
| AD Tech Unicorn PR Limited | Professional & scientific | 2017 |
| Adair Associates Limited | Professional & scientific | 2017 |
| Adair Limited | Professional & scientific | 2001 |
| Adam Dannan Associates Limited | Professional & scientific | 2022 |
| Adam Home Construction Limited | Construction | 2026 |
| Adam Perrin Sports Agency Ltd | Arts & recreation | 2012 |
| Adamas Global Limited | Information & communication | 2013 |
| Adamj&Co Ltd | Construction | 2020 |
| Adanero Limited | Professional & scientific | 2008 |
| Adapt and Build Ltd | Construction | 2024 |
| ADAPT2ABLE Limited | Construction | 2025 |
| Adaptive Function Ltd | Information & communication | 2016 |
| Adaptuslink Limited | Professional & scientific | 2008 |
| Adavni Limited | Real estate | 2026 |
| Adelaide House Freehold Limited | Households | 2019 |
| Adelphi Property Ltd | Real estate | 2023 |
| Adentro Limited | Administrative & support | 2016 |
| Adfs Solutions Ltd | Professional & scientific | 2025 |
| Adio Technology Ltd | Professional & scientific | 2020 |
| Adjacency Services Limited | Information & communication | 2016 |
| Adnitt Acoustic Services Limited | Professional & scientific | 2002 |
| Adnittlab Ltd | Professional & scientific | 2021 |
| Adnor Property Ltd | Real estate | 2024 |
| Adob Holdings Limited | Professional & scientific | 2017 |
| ADS Developments Ltd | Administrative & support | 2017 |
| ADS Management Limited | Construction | 2015 |
| Adsr Ltd | Information & communication | 2021 |
| Adubs 2 Z Rail Ltd | Transport & logistics | 2024 |
| Advance IT Group Limited | Information & communication | 2007 |
| Advance IT Solutions Limited | Information & communication | 2006 |
| Advance IT Systems Limited | Information & communication | 2006 |
| Advance Property Group Limited | Construction | 2026 |
| Advanced Access Media Ltd | Construction | 2021 |
| Advanced Access Platforms Ltd | Construction | 2007 |
| Advanced Eco Lifts Ltd | Construction | 2021 |
| Advanced Spider Lift Ltd | Construction | 2021 |
| Advantage Concrete Company Ltd | Manufacturing | 2006 |
| Advantage Properties Ltd | Construction | 2019 |
| Adventure Network Holdings Limited | Financial services | 2018 |
| ADX3D Media Ltd | Information & communication | 2026 |
| AE Presents Ltd | Administrative & support | 2023 |
| AE Solutions London Limited | Construction | 2025 |
| Aecon (UK) Limited | Professional & scientific | 2013 |
| Aeolus Drone Cleaning Ltd | Administrative & support | 2025 |
| Aeoneum Estate Limited | Real estate | 2025 |
| Aeoneum Limited | Professional & scientific | 2022 |
| Aero Wings Travel Ltd | Administrative & support | 2025 |
| Aerodance Ltd | Arts & recreation | 1998 |
| Aesthetic Elements Ltd | Other services | 2021 |
| Aesthetics and Beauty Teaching Academy Ltd | Other services | 2018 |
| Aesthetics and Rhetoric Ltd. | Professional & scientific | 2023 |
| Aether Lighting Limited | Manufacturing | 2008 |
| AF Fibre Ltd | Information & communication | 2022 |
| Affinityav Ltd | Wholesale & retail | 2025 |
| Affinitysmith Limited | Administrative & support | 2010 |
| African Sun Namibia Ltd | Agriculture & fishing | 2023 |
| African Sun SA Ltd | Agriculture & fishing | 2023 |
| AGA Technologies Limited | Information & communication | 2022 |
| Agapi Ltd | Hospitality | 2000 |
| AGE Concern Epsom & Ewell | Information & communication | 2010 |
| Agent Black & Co Ltd | Administrative & support | 2018 |
| AGF Consultancy Ltd | Professional & scientific | 2021 |
| Agha Motor Associates Limited | Other services | 2018 |
| Agile Security OPS Ltd | Professional & scientific | 2021 |
| AGJ Developments Ltd | Real estate | 2024 |
| Agori Limited | Professional & scientific | 2025 |
| Agrya UK Limited | Wholesale & retail | 2016 |
| AGS Cleaning Solutions Ltd | Wholesale & retail | 2025 |
| AHA London Ltd | Administrative & support | 2022 |
| Ahaghara Eyesoptics Ltd | Health & social care | 2022 |
| Ahead HR - Selection and Assessment Limited | Administrative & support | 2011 |