| Aatitech Ltd | Information & communication | 2025 |
| Aatom Limited | Administrative & support | 2006 |
| Aatom Recruitment Ltd | Administrative & support | 2009 |
| Aavi Management Limited | Professional & scientific | 2018 |
| Aawan Business Partnering Limited | Professional & scientific | 2011 |
| Aaya FRC Limited | Information & communication | 2015 |
| Aayal Ltd | Wholesale & retail | 2026 |
| Aayush Enterprises Ltd | Other services | 2015 |
| AB Construction (UK) Ltd | Construction | 2014 |
| AB Cyber Security Limited | Information & communication | 2024 |
| AB Developer Limited | Construction | 2026 |
| AB Events Ltd | Administrative & support | 2022 |
| AB Farma Ltd | Administrative & support | 2012 |
| AB Gynae Limited | Health & social care | 2021 |
| AB Joinery Ltd | Manufacturing | 2016 |
| AB Rolfe Limited | Arts & recreation | 2025 |
| AB Strategy Consulting Ltd | Professional & scientific | 2024 |
| AB Thakkar General Services Ltd | Hospitality | 2023 |
| AB14 Global Limited | Wholesale & retail | 2023 |
| ABA Daily Dose Ltd | Other services | 2022 |
| ABA Digital Ltd | Information & communication | 2019 |
| ABA London Limited | Real estate | 2026 |
| Abacus Corporate Finance Limited | Financial services | 2016 |
| Abacus Estates (KR) Ltd | Real estate | 2026 |
| Abacus Westbourne Limited | Financial services | 2006 |
| Abaj Corporation Ltd | Construction | 2022 |
| Abakhulu Limited | Financial services | 2024 |
| Abalfadhltv | Professional & scientific | 2021 |
| Aban Healthcare Limited | Wholesale & retail | 2014 |
| Abaseen Ltd | Hospitality | 2025 |
| ABB Capital Holdings Limited | Real estate | 2024 |
| Abban Enterprises UK Ltd | Construction | 2024 |
| Abbas & Co UK Ltd | Professional & scientific | 2014 |
| Abbas Corporation Limited | Other services | 2019 |
| Abbasi Investments Ltd | Real estate | 2020 |
| Abbawy (F & S) Limited | Professional & scientific | 2018 |
| Abbess Roding DEV Ltd | Real estate | 2026 |
| Abbey & Bodiam Management Company Limited | Households | 2014 |
| Abbey Clinical Limited | Health & social care | 2023 |
| Abbey Groves Investment Limited | Real estate | 2024 |
| Abbey MAC Home Improvements Limited | Construction | 2007 |
| Abbeybeck Estates Ltd | Real estate | 2002 |
| Abbeyfields Manor Ltd | Hospitality | 2019 |
| Abbeymead Mews Management Company Limited | Households | 2010 |
| Abbi Investments Ltd | Real estate | 2016 |
| Abbi Properties Ltd | Real estate | 2016 |
| Abbitron Ltd | Transport & logistics | 2023 |
| Abbots Enterprise Ltd | Wholesale & retail | 2016 |
| Abbots Langley DS Limited | Health & social care | 2026 |
| Abbotshill Food and Wine Limited | Hospitality | 2015 |
| Abbotswood Partners Ltd | Real estate | 2022 |
| Abbott & Harris Solicitors Ltd | Professional & scientific | 2020 |
| Abbotts Armstrong Partnership Limited | Administrative & support | 1986 |
| Abby & Partners Ltd | Information & communication | 2025 |
| ABC Apartments Estate Limited | Real estate | 2020 |
| ABC Construction Consultants Limited | Professional & scientific | 2011 |
| ABC Controls Ltd | Professional & scientific | 2007 |
| ABC Refrigeration Supplies Limited | Energy | 2026 |
| ABC UK Properties Ltd | Households | 2019 |
| Abcd Electrical Services From a to Z Limited | Construction | 2014 |
| Abconsultancy Services Ltd | Information & communication | 2008 |
| Abcz Consulting Limited | Information & communication | 2013 |
| Abdel Haja Ltd | Wholesale & retail | 2024 |
| Abdi & Abdi Limited | Professional & scientific | 2012 |
| Abdul Hannan Traders UK Ltd | Wholesale & retail | 2024 |
| Abdullahenterprises PVT Limited | Hospitality | 2026 |
| Abdulls Ltd | Professional & scientific | 2017 |
| Abel Building Ltd | Construction | 2020 |
| Abel Realty Holdings Ltd | Real estate | 2018 |
| Abelia Limited | Health & social care | 2013 |
| Abelini Limited | Wholesale & retail | 2017 |
| Abell Chemist Limited | Wholesale & retail | 2003 |
| Abell Pharma Ltd | Wholesale & retail | 2024 |
| Aben Europe Limited | Manufacturing | 2014 |
| Abercorn Design Studio Ltd | Professional & scientific | 2011 |
| Abex Advanced Ltd | Wholesale & retail | 2020 |
| Abex Infoway (Europe) Limited | Wholesale & retail | 2000 |
| Abeya Star Limited | Real estate | 2021 |
| Abfa Ventures Ltd | Information & communication | 2022 |
| Abhishek Healthcare Limited | Information & communication | 2023 |
| ABI Fast Food Limited | Hospitality | 2011 |
| ABI Jewellers Ltd | Wholesale & retail | 2018 |
| Abidamunir Properties Ltd | Real estate | 2019 |
| Abidamunir Properties Management Ltd | Real estate | 2022 |
| Abilities 3E Staffing Ltd | Health & social care | 2021 |
| Abilities Development Ltd | Education | 2010 |
| Abis Cash & Carry Limited | Wholesale & retail | 2010 |
| Abishiya Ltd | Wholesale & retail | 2026 |
| Abiz Cash & Carry Limited | Transport & logistics | 2010 |
| ABJ International Limited | Real estate | 2015 |
| ABJ Services Ltd | Wholesale & retail | 2025 |
| ABL Recruitment Limited | Administrative & support | 2017 |
| ABL UK Limited | Information & communication | 1992 |
| Able Appliances Limited | Other services | 2015 |
| Able at Home Care Ltd | Health & social care | 2019 |
| Able Nest Supported Living Services Ltd | Health & social care | 2025 |
| Able Plant Services Ltd. | Construction | 2000 |
| Able Rubbish Clearance Limited | Other services | 2006 |
| ABLE4YOU Ltd | Administrative & support | 2016 |
| Ablegrange (Wembley) Limited | Health & social care | 1999 |