| Abbott Brothers Holdings Ltd | Financial services | 2025 |
| Abbotts Freight Ltd | Extraterritorial | 2025 |
| Abbotts Heath Management Co. Limited | Households | 1986 |
| ABC Catering Ltd | Wholesale & retail | 2019 |
| ABD Handyman Services Ltd | Construction | 2021 |
| Abee Property Ltd | Real estate | 2025 |
| Abendsons Ltd | Professional & scientific | 2014 |
| Abhr Consultancy Ltd | Professional & scientific | 2023 |
| ABI Nurseries Limited | Education | 2010 |
| Abi's Medical Services Ltd | Health & social care | 2023 |
| Abidam Limited | Health & social care | 2023 |
| Abim Medics Ltd | Health & social care | 2023 |
| Abims-Precious Ventures (UK) Ltd | Health & social care | 2021 |
| Ablessed Ltd | Health & social care | 2021 |
| ABM Building Group Ltd | Construction | 2026 |
| ABN Medical Services Limited | Health & social care | 2017 |
| ABN Private Limited | Real estate | 2024 |
| ABO Adam Limited | Wholesale & retail | 2022 |
| Abonyi EJ Medical Service Ltd | Health & social care | 2026 |
| ABP Design and Management Limited | Professional & scientific | 2021 |
| Abrahams Real Property (London) Limited | Real estate | 2013 |
| Abrahams Real Property Limited | Real estate | 2013 |
| Absher Ltd | Wholesale & retail | 2024 |
| Absolute Building Contracts Ltd | Construction | 2019 |
| Absolute Interiors Commercial Flooring Limited | Construction | 2016 |
| Absolute Interiors Group Limited | Construction | 1999 |
| Absolute Interiors Properties Limited | Real estate | 2017 |
| Absolutely Stuffed Cookies Limited | Manufacturing | 2025 |
| Abstractions Holdings Ltd | Financial services | 2018 |
| Abundant Living Digital Healthcare Advisory Limited | Professional & scientific | 2026 |
| AC Heating & Plumbing Solutions Ltd | Construction | 2022 |
| AC Voltage Limited | Other services | 2017 |
| Acacia Coaching Ltd | Professional & scientific | 2023 |
| Acacia Electrical Ltd | Construction | 2025 |
| Accelerated Diagnostics Limited | Professional & scientific | 2025 |
| Access Conveyancing Services Ltd | Professional & scientific | 2022 |
| ACCOUNT4U Limited | Professional & scientific | 2012 |
| Accountancy & Bookkeeping Ltd | Professional & scientific | 2022 |
| Accurate Limited | Professional & scientific | 2026 |
| Ace Clinical Solutions Ltd | Health & social care | 2026 |
| Ace Groundworks & Driveways Limited | Construction | 2015 |
| Ace Shopfitters Limited | Manufacturing | 1984 |
| Acea Homes Ltd | Real estate | 2024 |
| Acelink Limited | Real estate | 2022 |
| Acemodel Ltd | Professional & scientific | 2013 |
| ACH Healthcare Ltd | Administrative & support | 2017 |
| ACH Healthcare Recruitment Ltd | Health & social care | 2022 |
| ACH Training Academy Ltd | Health & social care | 2024 |
| Achakili Group Limited | Financial services | 2026 |
| Achievers Cleaning Limited | Administrative & support | 2025 |
| Achievers Point Academy Limited | Information & communication | 2017 |
| Achota ONU Ltd | Arts & recreation | 2019 |
| Aciace Medical Services Limited | Health & social care | 2024 |
| Acms Property Limited | Real estate | 2022 |
| ACN Health Limited | Health & social care | 2025 |
| Acorn Building and Maintenance Ltd | Construction | 2026 |
| Acorn House Residential Home Limited | Health & social care | 2005 |
| Acquistare Limited | Transport & logistics | 2024 |
| Acquitas Partners Ltd | Professional & scientific | 2026 |
| ACR Transport Ltd | Manufacturing | 2019 |
| Acral Gears Limited | Professional & scientific | 1976 |
| Acris Court Management Company Limited | Households | 2007 |
| Across World UK Ltd. | Wholesale & retail | 2005 |
| ACS Xtra Space Ltd | Construction | 2021 |
| ACT Smart Construction Ltd | Construction | 2022 |
| ACTIV8 FUN (Peterborough) Limited | Arts & recreation | 2025 |
| Active Motorparts Ltd | Wholesale & retail | 2026 |
| Activealldayfitness Ltd | Other services | 2025 |
| Activecore Education Ltd | Education | 2025 |
| Activus Safety Training and Consulting Ltd | Professional & scientific | 2011 |
| Acumen Trade Limited | Professional & scientific | 2009 |
| AD M Capital Investments Limited | Financial services | 2026 |
| AD Total FAB Ltd | Manufacturing | 2021 |
| Adac Energy Limited | Construction | 2022 |
| Adam Blackburn Painting & Decorating Ltd | Construction | 2018 |
| Adam Meere House RTM Company Limited | Households | 2025 |
| Adams Motors Garage Ltd. | Wholesale & retail | 2004 |
| Adapt Flow Deliver Consultancy Ltd | Professional & scientific | 2024 |
| Adapt Plumbing and Heating Services Ltd | Construction | 2023 |
| Adcl Enterprises Limited | Information & communication | 2016 |
| ADD Development Limited | Construction | 2010 |
| Added Space Ltd | Construction | 2018 |
| Addie's Party Squad Ltd | Extraterritorial | 2020 |
| Addlestone House Management Company Limited | Households | 2017 |
| Addressing & Mailing Solutions Limited | Wholesale & retail | 2003 |
| Adejom Helping Hands Ltd | Health & social care | 2025 |
| Adejom Ltd | Wholesale & retail | 2014 |
| Adelphi Cleaning Company Ltd | Administrative & support | 2013 |
| Adelphi Property Services Ltd | Water & waste | 2019 |
| Ademaj Construction Ltd | Construction | 2023 |
| Ademola Limited | Health & social care | 2023 |
| Adeola Consult Ltd | Health & social care | 2021 |
| Adeoloni Healthcare Limited | Health & social care | 2023 |
| Adescotoks Limited | Health & social care | 2025 |
| Adesdos Ltd | Health & social care | 2019 |
| Adesso Communications Limited | Information & communication | 2015 |
| Adetade Ltd | Real estate | 2025 |
| Adexx Limited | Construction | 2017 |
| Adico Care Ltd | Health & social care | 2013 |
| Adimal Ltd | Health & social care | 2013 |