| A&H Properties Management Ltd | Real estate | 2021 |
| A&M Jewllers Limited | Wholesale & retail | 2025 |
| A&M Skills Ltd Ltd | Construction | 2023 |
| A&R International Trading Ltd | Manufacturing | 2019 |
| A. Skarpa Limited | Health & social care | 2026 |
| A.M.Sheer Ltd | Hospitality | 2023 |
| A.S. Procurement Ltd | Professional & scientific | 2024 |
| A.V.I Protection Ltd | Construction | 2023 |
| A.W.Properties Limited | Real estate | 1959 |
| A1 Rail Services Ltd | Construction | 2014 |
| A1 Topman UK Ltd | Other services | 2022 |
| A1 UK Consultancy Ltd | Information & communication | 2009 |
| A2Z Herts Cars Ltd | Transport & logistics | 2020 |
| AA Dairies Ltd | Wholesale & retail | 2012 |
| AA Property Portfolio Ltd | Real estate | 2022 |
| AA Trade Company Ltd | Wholesale & retail | 2014 |
| AAC Electrical Projects Limited | Construction | 2021 |
| AAC Group Projects Ltd | Construction | 2016 |
| AAC Projects Limited | Construction | 2006 |
| Aagtrades Limited | Wholesale & retail | 2023 |
| Aaradhya Asian Supermarket Ltd | Wholesale & retail | 2026 |
| Aarow Group Limited | Construction | 2020 |
| Aarvi GRA Services Limited | Professional & scientific | 2018 |
| Aas&Sons Ltd | Households | 2025 |
| Aask Property Ventures Ltd | Real estate | 2021 |
| Aays Technologies UK Limited | Professional & scientific | 2020 |
| AB Residential Ltd | Real estate | 2024 |
| Abacus Electrical Ltd | Construction | 2016 |
| Abareels Limited | Households | 1977 |
| Abbey Consult Ltd | Other services | 2016 |
| Abbeymead Building Limited | Construction | 2007 |
| Abbeyset Limited | Information & communication | 1992 |
| Abbotswood Property Services Ltd | Construction | 2015 |
| ABC Care Limited | Health & social care | 2022 |
| Aberfoyle Properties Ltd | Real estate | 2021 |
| ABP Ireg Consulting Ltd | Information & communication | 2020 |
| Absolute Environment Ltd | Administrative & support | 2019 |
| Absolute Skin Aesthetics Ltd | Other services | 2024 |
| Absolutely Recruitment Holding Limited | Administrative & support | 2023 |
| Absolutely Recruitment Ltd | Administrative & support | 2008 |
| Abstract Safety Ltd | Administrative & support | 2020 |
| Acacia Point Capital Advisors Limited | Real estate | 2014 |
| Academic Group Ltd | Education | 2023 |
| Access to Globe Limited | Professional & scientific | 2006 |
| Accor Investments Ltd | Extraterritorial | 2018 |
| Accountverse Limited | Professional & scientific | 2022 |
| Acctechfin Consultancy Ltd | Professional & scientific | 2021 |
| Accurate Fixing Systems Limited | Construction | 2025 |
| Ace Prism Ventures Limited | Wholesale & retail | 2017 |
| Aced Group Limited | Administrative & support | 2020 |
| ACM Plumbing and Tiling Ltd | Other services | 2017 |
| ACT & Construct Ltd | Construction | 2023 |
| ACTIV8 Digital Limited | Administrative & support | 2015 |
| Active Brains Ltd | Information & communication | 2002 |
| Acumist Accounting Limited | Professional & scientific | 2014 |
| AD Astra Sports Management Ltd | Health & social care | 2020 |
| AD Carpets & Rugs Ltd | Wholesale & retail | 2025 |
| AD Carpets London Ltd | Other services | 2011 |
| AD Flooring Ltd | Construction | 2021 |
| Adam J Walker and Associates Ltd | Professional & scientific | 2009 |
| Adamo Joya Ltd | Wholesale & retail | 2021 |
| Addison Homecare Limited | Health & social care | 2025 |
| Addonova Limited | Professional & scientific | 2014 |
| ADE Trading Limited | Manufacturing | 2014 |
| Adem Cafe Ltd | Hospitality | 2025 |
| Adey Interiors Limited | Professional & scientific | 2017 |
| Adhoc Squads Ltd | Information & communication | 2025 |
| Adrena Austin Ltd | Professional & scientific | 2019 |
| Adrian Houston Limited | Professional & scientific | 2005 |
| Advanced Lighting Technologies Europe Limited | Professional & scientific | 1995 |
| Adventia Ltd | Information & communication | 2014 |
| Advise Community Ltd | Information & communication | 2016 |
| Advisertime Limited | Financial services | 2008 |
| AE3 Design & Build Limited | Construction | 2003 |
| Aedis LUF Ltd | Wholesale & retail | 2025 |
| Aedis SAT Ltd | Professional & scientific | 2025 |
| Aegion Limited | Professional & scientific | 2022 |
| Aequitas Packing (UK) Limited | Transport & logistics | 2014 |
| Aero Vote Security Print Ltd | Manufacturing | 2021 |
| Aesthetic Appeal Limited | Health & social care | 2018 |
| Aesthetic Document Services Ltd | Health & social care | 2018 |
| Aesthetic Medicine Clinic Ltd | Health & social care | 2012 |
| Aesthetics Made Easier Ltd | Professional & scientific | 2025 |
| Aether Run Club Ltd | Arts & recreation | 2026 |
| AEU UK Limited | Arts & recreation | 2021 |
| AF Performance UK Ltd | Construction | 2025 |
| Afro Ready Meals Ltd | Hospitality | 2021 |
| After Moon Yoga Ltd | Other services | 2023 |
| Agape S&P Ltd | Information & communication | 2009 |
| AGL Development Ltd | Agriculture & fishing | 2018 |
| Agno Smile Limited | Wholesale & retail | 2011 |
| Agos Consultancy Ltd | Information & communication | 2025 |
| Agos Investments Ltd | Real estate | 2021 |
| AGS Select Solutions Limited | Administrative & support | 2014 |
| Ahlm Holdings Limited | Financial services | 2024 |
| AHM Training Ltd | Education | 2022 |
| Aikardia Ltd | Information & communication | 2024 |
| Aimalabs Ltd | Information & communication | 2026 |
| Aims Solutions UK Limited | Professional & scientific | 2024 |
| Ainigma Holdings Ltd | Financial services | 2020 |