| A Word in Your EAR Writing Ltd | Arts & recreation | 2012 |
| A&C Logs Limited | Wholesale & retail | 2023 |
| A&Y Holdings Ltd | Financial services | 2022 |
| A-M Studio Ltd | Professional & scientific | 2016 |
| A.C.M.T. Limited | Water & waste | 2001 |
| A.D.S Plumbing & Heating SW Ltd | Construction | 2012 |
| A.G.& K.M.Spiers,Limited | Real estate | 1947 |
| A.H. Hale Limited | Wholesale & retail | 1975 |
| A.J. Champion & Sons (Haulage) Ltd | Transport & logistics | 2003 |
| A.J. Mechanical Handling Services Limited | Real estate | 1973 |
| A.M. Products Trading Company Limited | Manufacturing | 1999 |
| A.N.H Security Ltd | Administrative & support | 2021 |
| A.S Bath Private Hire Ltd | Transport & logistics | 2026 |
| A3C Limited | Information & communication | 2023 |
| A3L Partnership Limited | Construction | 2024 |
| A4 Asbestos Group Limited | Professional & scientific | 2020 |
| A4 Asbestos Limited | Water & waste | 2014 |
| A4 Asbestos Services Ltd | Water & waste | 2025 |
| AA Assessments and Consultancy Limited | Health & social care | 2025 |
| AA Certification Limited | Professional & scientific | 2013 |
| AA Foxfield Consulting Ltd | Professional & scientific | 2023 |
| AAA+ Solution Ltd | Wholesale & retail | 2022 |
| Aarbee Medical Ltd | Health & social care | 2024 |
| Aaron Evans Architects Limited | Professional & scientific | 1986 |
| Abacus Bowman Limited | Professional & scientific | 2011 |
| ABC Management Consulting Limited | Professional & scientific | 2014 |
| ABC Self Assessment Ltd | Information & communication | 2013 |
| Abdc Dog Walks Ltd | Other services | 2024 |
| Abell Nepp Architects Limited | Professional & scientific | 2014 |
| ABI Accounting Limited | Professional & scientific | 2016 |
| Abigail Grummitt Limited | Professional & scientific | 2011 |
| Able Scaffolding Bath Ltd | Construction | 2015 |
| Ablegatio Limited | Information & communication | 2016 |
| Ableweld Solutions Limited | Manufacturing | 2025 |
| Abney & Baker (Bath) Ltd | Health & social care | 2015 |
| Abney and Baker (Wiltshire) Ltd | Health & social care | 2020 |
| Abney and Baker Limited | Health & social care | 2015 |
| Abney and Gray Ltd | Administrative & support | 2015 |
| Abode Communications Limited | Professional & scientific | 2017 |
| Abrasives & Tooling 2 Industry Limited | Wholesale & retail | 2009 |
| Absolute Competitions Limited | Wholesale & retail | 2026 |
| Absolute Devotion Limited | Other services | 2025 |
| Abundant Marketing Ltd | Information & communication | 2012 |
| Abyssion Ltd | Wholesale & retail | 2025 |
| Academy of 3D Art Decoupage & Craft International Limited | Education | 2015 |
| Academy Plaza Limited | Construction | 2018 |
| Accelerate Driving School Ltd | Education | 2018 |
| Access Enabled Consulting Ltd | Professional & scientific | 2025 |
| Access Engineered Limited | Construction | 2023 |
| Accounting Advice Services Limited | Professional & scientific | 2015 |
| Accounting Advice Supplies Limited | Professional & scientific | 2014 |
| Accrue Investment Management Limited | Financial services | 2001 |
| Accrue Limited | Financial services | 2001 |
| Accrue Nominees (Exempt) Limited | Financial services | 2000 |
| Accrue Nominees Limited | Financial services | 2000 |
| Ace of Spades Limited | Administrative & support | 2002 |
| Ace Radiators Ltd | Wholesale & retail | 2025 |
| Acen Sales & Marketing Consultancy Ltd | Wholesale & retail | 2021 |
| Acer Accountancy Limited | Professional & scientific | 2012 |
| Achieve Awesome Ltd. | Real estate | 2012 |
| Achieve Breakthrough Limited | Professional & scientific | 2003 |
| Achieve Breakthrough Trustees Limited | Administrative & support | 2023 |
| Aclue Limited | Information & communication | 2023 |
| ACO (Bath) Limited | Energy | 2014 |
| Acorn 2 Oak Marketing Limited | Professional & scientific | 2014 |
| Acquaviva Plumbing & Heating Ltd | Construction | 2022 |
| Acredale Builders Limited | Construction | 1972 |
| Acres (Bath) Ltd | Agriculture & fishing | 2021 |
| Acrobatic Adventures CIC | Arts & recreation | 2024 |
| Action Investments Ltd | Real estate | 2023 |
| Action NET Zero CIC | Professional & scientific | 2020 |
| Active Health Consultants Limited | Health & social care | 2009 |
| Active Reality Ltd | Information & communication | 2019 |
| Active Thinking Limited | Professional & scientific | 2007 |
| Activepassive Energy Consultants Ltd | Professional & scientific | 2019 |
| Activesite Limited | Professional & scientific | 2024 |
| Activity Play Limited | Real estate | 1971 |
| AD & GC Investments Limited | Education | 2010 |
| AD Maiora Consulting Ltd | Extraterritorial | 2018 |
| Adam & Jones Ltd | Wholesale & retail | 2024 |
| Adam Lewis & Sons Limited | Real estate | 2025 |
| Adam's Apartments Ltd | Real estate | 2019 |
| Adamas Roofing Ltd | Construction | 2025 |
| ADB Safety and Training Limited | Professional & scientific | 2017 |
| Adco Limited | Administrative & support | 2012 |
| ADE Properties Limited | Real estate | 2019 |
| Adelard Steel Limited | Information & communication | 1997 |
| Adels Express Limited | Hospitality | 2022 |
| Adhl Holdings Limited | Professional & scientific | 2019 |
| Aditivo Ltd | Manufacturing | 2024 |
| Aditya Investments Limited | Real estate | 2019 |
| Adns Consultancy Ltd | Professional & scientific | 2024 |
| ADQ Limited | Real estate | 2014 |
| Adrian Logan Limited | Professional & scientific | 2013 |
| Advaita Vedanta Sadhana | Education | 2018 |
| Advalus Limited | Professional & scientific | 2003 |
| Advance Optics Limited | Wholesale & retail | 2017 |
| Advance Platform Ltd | Financial services | 2017 |
| Advance Scout Limited | Extraterritorial | 2023 |
| Advanced Motion Systems Ltd | Professional & scientific | 2020 |