| Absolute Building (Services) Ltd | Construction | 2014 |
| Absolute Calibration Limited | Professional & scientific | 1998 |
| Absolutely Brilliant Business Ltd | Information & communication | 2016 |
| Absolutely Brilliant Garages Ltd | Information & communication | 2016 |
| Absolutely Brilliant Supplies Ltd | Information & communication | 2016 |
| Abstract Object Limited | Information & communication | 2009 |
| ABT Retail Services Ltd | Information & communication | 2020 |
| Abzu Electronics Ltd | Manufacturing | 2024 |
| AC Aerotech Ltd | Professional & scientific | 2022 |
| AC Doyle Ltd | Information & communication | 2024 |
| AC Property Holdings Ltd | Real estate | 2015 |
| AC Retro Vintage Clothes and Collectibles Ltd | Wholesale & retail | 2026 |
| Accelerator Limited | Administrative & support | 2003 |
| Accent Ltd | Information & communication | 2009 |
| Access Group Holdings Ltd | Construction | 2024 |
| Access Infrastructure Group Ltd | Financial services | 2024 |
| Access Training Group Ltd | Other services | 2024 |
| Accessible Oceans Ltd | Transport & logistics | 2025 |
| Accevo Accountancy Limited | Professional & scientific | 2012 |
| Acclaim Freight Services Limited | Transport & logistics | 2010 |
| Accommodation by DJT Ltd | Real estate | 2023 |
| Accountancy Evolution Limited | Professional & scientific | 2024 |
| Accountancy Supermarket Limited | Administrative & support | 2012 |
| Accountant Sea Ltd | Financial services | 2023 |
| Accounting Numbers Limited | Professional & scientific | 2025 |
| Accrington Specsavers Hearcare Limited | Wholesale & retail | 2019 |
| Accrington Specsavers Limited | Wholesale & retail | 1992 |
| Accrington Visionplus Limited | Wholesale & retail | 1992 |
| Accurate Collections Ltd | Wholesale & retail | 2024 |
| Ace Catering Engineers Ltd | Administrative & support | 2003 |
| Ace Service Centre Ltd | Wholesale & retail | 2006 |
| Acec Services Ltd | Construction | 2019 |
| Acei Pools Limited | Administrative & support | 2026 |
| Acethetic Ltd | Other services | 2019 |
| Acheong Ltd | Real estate | 2017 |
| ACL Homes Ltd | Real estate | 2019 |
| ACL Property Holdings Ltd | Real estate | 2021 |
| Acocks Green Specsavers Limited | Wholesale & retail | 2014 |
| Acog Freehold Ltd | Real estate | 2022 |
| Acomb Specsavers Limited | Wholesale & retail | 2012 |
| Acorn Investment and Trading Ltd | Real estate | 2020 |
| Acorn Removals Limited | Other services | 2014 |
| Acorn Traditional Windows Limited | Construction | 2024 |
| ACP Construction Ltd | Construction | 2016 |
| Acquisitions Alliance Group Ltd | Real estate | 2023 |
| Acting UP Drama School Limited | Arts & recreation | 2016 |
| Active Academy Ltd | Wholesale & retail | 2013 |
| Active Finance UK Ltd | Financial services | 2010 |
| Active Freight Worldwide Ltd | Transport & logistics | 2014 |
| Active Investments UK Ltd | Real estate | 2015 |
| Active Mortgages (UK) Ltd | Financial services | 2014 |
| Active Step Healthcare Limited | Health & social care | 2013 |
| Acton Specsavers Limited | Wholesale & retail | 2016 |
| ACW Insight Ltd | Professional & scientific | 2024 |
| AD & JD Property Ltd | Real estate | 2019 |
| AD Finance Ltd | Financial services | 2026 |
| AD Learning Consultancy Ltd | Professional & scientific | 2015 |
| AD Marine Services Limited | Administrative & support | 2006 |
| AD60BOS Limited | Professional & scientific | 2025 |
| Adam Gardiner Limited | Professional & scientific | 2007 |
| Adam Rolls Tree Services Ltd | Agriculture & fishing | 2021 |
| Adams Waste Limited | Extraterritorial | 2000 |
| Adamson International Ltd | Professional & scientific | 2023 |
| Adander Limited | Real estate | 2025 |
| Adaptfitness Ltd | Arts & recreation | 2025 |
| Adbt Machining Ltd | Manufacturing | 2026 |
| Additional Self Storage Limited | Other services | 2007 |
| Addlestone Specsavers Limited | Wholesale & retail | 2019 |
| Adept Care & Education Limited | Health & social care | 2005 |
| Adept Healthcare Limited | Administrative & support | 2013 |
| Adept Medicare Limited | Professional & scientific | 2006 |
| Adept Residential Care Limited | Education | 2006 |
| Aderco Limited | Professional & scientific | 2012 |
| Adese Recycling Ltd | Other services | 2024 |
| ADG Home Rental Limited | Real estate | 2025 |
| ADK Removals & Storage Ltd | Transport & logistics | 2018 |
| ADL Hair Limited | Other services | 2001 |
| Admiral Commercial Cleaning Group Ltd | Administrative & support | 2020 |
| Admiral Hampshire Properties Ltd | Real estate | 2025 |
| Adopted Intelligence Ltd | Manufacturing | 2026 |
| Adrift Covers Limited | Manufacturing | 2017 |
| ADS Data Services Ltd | Professional & scientific | 2007 |
| Adspec Limited | Professional & scientific | 2025 |
| Adsuccess Group Limited | Professional & scientific | 2023 |
| Adsure Services PLC | Professional & scientific | 2022 |
| Adtechlab Ltd | Professional & scientific | 2020 |
| Adun Engineering Ltd | Manufacturing | 2018 |
| Advaco Investments Limited | Financial services | 2021 |
| ADVANCE365 Security Ltd | Construction | 2025 |
| Advanced Animation Academy Ltd | Professional & scientific | 2021 |
| Advanced Mortgage Lending Ltd | Financial services | 2004 |
| Advanced Plastics (Intermediate 1) Limited | Professional & scientific | 2009 |
| Advanced Plastics (NW) Limited | Manufacturing | 2013 |
| Advanced Plastics (South) Limited | Manufacturing | 1987 |
| Advent Technical Ltd | Professional & scientific | 2015 |
| Adventure Camp Limited | Information & communication | 2015 |
| Advo Health Limited | Health & social care | 2024 |
| Advoca Health Ltd | Information & communication | 2025 |
| ADW ARC Group Holdings Limited | Wholesale & retail | 2021 |
| Aegina Technologies Limited | Manufacturing | 2000 |