| A.T. Poeton & SON Limited | Administrative & support | 1953 |
| A1 Architecture Ltd | Professional & scientific | 2018 |
| A1 Cogent Logistics Limited | Transport & logistics | 2025 |
| A1 Social Care Ltd | Administrative & support | 2022 |
| A1209 Ltd | Hospitality | 2019 |
| A2B Concrete Pumping Limited | Administrative & support | 2014 |
| A3A.AGENCY for the Third AGE Limited | Professional & scientific | 2021 |
| A3M Quality Solutions Limited | Information & communication | 2023 |
| A6 Labs Limited | Information & communication | 2021 |
| AA Gardening Tree Surgeons Ltd | Arts & recreation | 2019 |
| AA Tree Surgeons & Stump Ltd | Arts & recreation | 2024 |
| Aa-Orthotrauma Ltd | Health & social care | 2018 |
| AAA Electrical Specialist Ltd | Construction | 2018 |
| AAA Enterprises (Gloucester) Ltd | Wholesale & retail | 2021 |
| AAA LG Ltd | Administrative & support | 2011 |
| AAA Project Controls Ltd | Professional & scientific | 2023 |
| AAA South West Management Limited | Construction | 2013 |
| Aaasiddiqui Ltd | Real estate | 2025 |
| AAB Transport Ltd | Transport & logistics | 2022 |
| Aada Clothing and Home Decor Limited | Wholesale & retail | 2023 |
| Aaizah Ltd | Hospitality | 2024 |
| AAJ Sharma Properties Limited | Real estate | 2025 |
| Aalam Properties Limited | Real estate | 2011 |
| AAP Realestate Ltd | Real estate | 2021 |
| Aarupadai Properties Ltd | Real estate | 2017 |
| Aashvi Properties Ltd | Real estate | 2019 |
| AAW Capital Ltd | Real estate | 2019 |
| Aayat Online Purchasing Ltd | Wholesale & retail | 2025 |
| AB & NL Investment Ltd | Real estate | 2022 |
| AB Carpets and Flooring Ltd | Construction | 2020 |
| AB Cotswold Property Group Limited | Real estate | 2025 |
| AB Motor Vehicle Services Ltd | Wholesale & retail | 2014 |
| Ababex Limited | Professional & scientific | 1987 |
| Abaqus Limited | Professional & scientific | 2016 |
| Abatis Legal Consultants Ltd | Professional & scientific | 2024 |
| Abbey Accountancy Ltd | Professional & scientific | 2007 |
| Abbey Cereals Limited | Wholesale & retail | 2010 |
| Abbey Kitchens Cotswolds Ltd | Manufacturing | 2026 |
| Abbey Loos Limited | Administrative & support | 2009 |
| Abbey Sports and Leisure Ltd | Education | 2003 |
| Abbeycare Holdings Ltd | Other services | 2017 |
| Abbeydale Court Management Limited | Households | 1983 |
| Abbeymead Dental Care Ltd | Health & social care | 2012 |
| Abbeysmart Ltd | Administrative & support | 2021 |
| Abbie Doctor Aesthetics Ltd | Other services | 2023 |
| ABC Barber Ltd | Other services | 2026 |
| Abcomplete Ltd | Administrative & support | 2010 |
| Abdul Habib Ltd | Wholesale & retail | 2025 |
| Abfab Flooring Ltd | Wholesale & retail | 2012 |
| ABI Change Logic CS Limited | Administrative & support | 2023 |
| Ability Software Consultants Limited | Information & communication | 2003 |
| Abilla Construction Limited | Construction | 2018 |
| Above and Beyond Logistics Ltd | Transport & logistics | 2019 |
| ABS Heating Services Limited | Professional & scientific | 2017 |
| Absolute Build and Construction Ltd | Real estate | 2024 |
| Absolute Compressor Services Limited | Administrative & support | 2009 |
| Absolute Creative Marketing Limited | Professional & scientific | 2007 |
| Absolute Guff Ltd | Extraterritorial | 2021 |
| Absolute Utilities Limited | Professional & scientific | 2019 |
| Absolutely Personal Ltd | Wholesale & retail | 2024 |
| AC Andrew Logistic Ltd | Transport & logistics | 2016 |
| AC Automotive Limited | Wholesale & retail | 2004 |
| AC Health Care Group Ltd | Administrative & support | 2022 |
| AC Plumbing & Heating (SW) Ltd | Construction | 2012 |
| ACA Enterprises Limited | Hospitality | 2010 |
| Academy of Human Resource and Management Practitioners Ltd | Education | 2022 |
| ACARE4U Limited | Health & social care | 2023 |
| Acasandrei Trans Ltd | Transport & logistics | 2021 |
| Acc-Sel Genetics Limited | Agriculture & fishing | 2001 |
| Accede Financial Services Ltd | Agriculture & fishing | 2010 |
| Accellier Limited | Information & communication | 2012 |
| Access AHP Ltd | Health & social care | 2026 |
| Access Underwriting Limited | Financial services | 1999 |
| Accountrix Limited | Professional & scientific | 2014 |
| Accovia Accounting Ltd | Professional & scientific | 2026 |
| Accura Surveys Limited | Information & communication | 2005 |
| Accurate Boiler Services Ltd | Manufacturing | 2025 |
| Accutec Limited | Manufacturing | 2006 |
| Ace (SW) Ltd | Other services | 2020 |
| Ace Clean and Hire Limited | Administrative & support | 2025 |
| Ace Cleaning Contracts Limited | Administrative & support | 2007 |
| Ace Cross Country Ltd | Arts & recreation | 2016 |
| Ace Group (SW) Ltd | Construction | 2023 |
| ACG Art Limited | Wholesale & retail | 2015 |
| ACG Commercial Limited | Professional & scientific | 2016 |
| Achieve in Mentoring CIC | Education | 2025 |
| Achievers Tutoring Ltd | Education | 2020 |
| Ackerman H Limited | Wholesale & retail | 2025 |
| ACM Accounting Limited | Professional & scientific | 2017 |
| Acorn Black Investments Holdings Limited | Administrative & support | 2023 |
| Acorn Broker Network Limited | Financial services | 2025 |
| Acorn Capital Partners Limited | Financial services | 1999 |
| Acorn to Oak Homecare Limited | Health & social care | 2018 |
| ACP First Ltd | Health & social care | 2022 |
| Acsa Developments Ltd | Construction | 2017 |
| ACT (Fasteners and Components) Limited | Wholesale & retail | 1988 |
| ACT Local Ltd | Professional & scientific | 2023 |
| Actionplan Compliance Services Ltd | Financial services | 2018 |
| Activ-Step Limited | Professional & scientific | 2004 |
| ACTIV-X360 Limited | Arts & recreation | 2025 |