| 01 Handyman Ltd | Construction | 2015 |
| 17SMR Management Ltd | Households | 2024 |
| 2FA Properties Limited | Real estate | 2022 |
| 357 Management Ltd | Administrative & support | 2024 |
| 39 Seaview RTM Company Limited | Households | 2019 |
| 3A'S RMN Limited | Extraterritorial | 2022 |
| 4 Law Property Ltd | Real estate | 2024 |
| 4URTESTING Ltd | Professional & scientific | 2024 |
| 5 Star Barber I Ltd | Other services | 2023 |
| 70 Drinks Ltd | Wholesale & retail | 2023 |
| 80 Drinks Ltd | Wholesale & retail | 2025 |
| 8A Church Street Limited | Professional & scientific | 2012 |
| A & J Development Enterprises Ltd | Real estate | 2026 |
| A a Buckingham Limited | Construction | 2011 |
| A B Electrics (UK) Limited | Construction | 2002 |
| A Jutzeler (U.K.) Limited | Construction | 1987 |
| A K M Cooling Services Ltd | Energy | 2020 |
| A L B Transport&Motor-Trade Ltd | Transport & logistics | 2019 |
| A Touch of Frost Ltd | Construction | 2010 |
| A&A Building Solutions Ltd | Construction | 2019 |
| A&K Food Services Ltd | Hospitality | 2026 |
| A&M Building Ltd | Construction | 2026 |
| A&O Building Limited | Construction | 2024 |
| A,Bto C Ltd | Transport & logistics | 2025 |
| A-B Administration Limited | Professional & scientific | 2018 |
| A-Sisterhood Ltd | Other services | 2017 |
| A. Abbott and Sons (Rushden) Limited | Other services | 1949 |
| A. G. Pentelow Groundworks Limited | Construction | 2011 |
| A. Seaton Electrical Ltd | Construction | 2011 |
| A.A.A Constraction Ltd | Construction | 2022 |
| A.B.Mills Ltd | Transport & logistics | 2024 |
| A.C. Autos - Remapping, Services and Repairs Ltd | Wholesale & retail | 2021 |
| A.E.M. Products Limited | Manufacturing | 1995 |
| A4 Telecoms Ltd | Construction | 2023 |
| AA Cash & Carry Limited | Wholesale & retail | 2012 |
| Aa.Navira Ltd | Wholesale & retail | 2025 |
| Aajg Enterprises Ltd | Hospitality | 2024 |
| Aarcon Limited | Construction | 2025 |
| Aart Shop Ltd | Manufacturing | 2026 |
| AAS Advanced Aerial Services Ltd | Construction | 2017 |
| AB Change Management Ltd | Professional & scientific | 2024 |
| ABB Fabs Ltd | Manufacturing | 2020 |
| Abbey Plumbing & Electric Ltd | Construction | 2019 |
| Abbey Publishing Ltd | Information & communication | 2013 |
| Abbott Fabrications Limited | Manufacturing | 1999 |
| ABC Builders Limited | Real estate | 1999 |
| ABE Consultancy Limited | Information & communication | 2006 |
| Abml Limited | Real estate | 2008 |
| AC Electrical Contracting Limited | Construction | 2021 |
| Access Fertility Bidco Limited | Financial services | 2019 |
| Access Fertility Greece Limited | Health & social care | 2020 |
| Access Fertility International Limited | Health & social care | 2018 |
| Access Fertility Ireland Limited | Health & social care | 2018 |
| Access Fertility Poland Limited | Health & social care | 2020 |
| Access Fertility Spain Limited | Health & social care | 2020 |
| Access Fertility Topco Limited | Financial services | 2019 |
| Accon Professional Accountancy Services Ltd | Professional & scientific | 2016 |
| Acer Accountancy Services Limited | Professional & scientific | 2015 |
| Acer Accountants Ltd | Professional & scientific | 2024 |
| Acme Audio Ltd | Information & communication | 2010 |
| Acorn Lofts.Com Ltd | Construction | 2010 |
| Acres Cover Limited | Financial services | 2023 |
| Acres Insurance Brokers Ltd | Financial services | 2018 |
| Acres Investments Limited | Financial services | 2025 |
| Acres South Ltd | Financial services | 2019 |
| ACTIVE4LIFE Care Ltd | Health & social care | 2026 |
| Acumen+ Accountants Ltd | Professional & scientific | 2024 |
| AD Car Wash Ltd | Other services | 2024 |
| Adams Apple Fresh Produce Limited | Wholesale & retail | 2012 |
| Adams MRO Solutions Limited | Professional & scientific | 2024 |
| Addacas Accounting Limited | Professional & scientific | 2019 |
| Addingtons Associates Limited | Construction | 2011 |
| ADE Autodesign Limited | Wholesale & retail | 2020 |
| ADELINA2001 Limited | Construction | 2018 |
| ADK Homes Limited | Real estate | 2024 |
| ADL Properties Limited | Professional & scientific | 1979 |
| Adlss Limited | Construction | 2017 |
| ADM Care Homes Limited | Health & social care | 2006 |
| Adman Alpha Limited | Information & communication | 2023 |
| Admi Trans Ltd | Transport & logistics | 2024 |
| Adtf Limited | Construction | 2025 |
| Advanced Scaffold Inspection Ltd | Construction | 2025 |
| Advent Planning Limited | Real estate | 2017 |
| Aeccp Limited | Administrative & support | 2016 |
| Aeriva Ltd | Construction | 2025 |
| Affinity Pro Health Limited | Health & social care | 2013 |
| Agilivery Limited | Professional & scientific | 2023 |
| AGK Solutions Ltd | Administrative & support | 2008 |
| AGM Lexmar Ltd | Transport & logistics | 2022 |
| Agonges Limited | Professional & scientific | 2025 |
| AH Multitrade Ltd | Construction | 2025 |
| AI Web Developments Limited | Information & communication | 2025 |
| Aiden James Motor Service Limited | Wholesale & retail | 2019 |
| Air Conditioning One Ltd | Wholesale & retail | 2013 |
| Airbytes Communications Limited | Information & communication | 2022 |
| Airbytes Network Limited | Information & communication | 2019 |
| Aiso Consulting Ltd | Construction | 2012 |
| AJ Premium Property Ltd | Real estate | 2025 |
| AJB Catering Ltd | Hospitality | 2022 |
| AJH Consulting Services Ltd | Professional & scientific | 2018 |