| A.P. Charles Investments Ltd | Information & communication | 1988 |
| A.R.T Scaffolding Ltd | Construction | 2021 |
| A1 Accident Management Limited | Extraterritorial | 2003 |
| A1 Auto Group Limited | Extraterritorial | 2003 |
| A1 Hire (UK) Limited | Extraterritorial | 2003 |
| A1 Property Repairs Ltd | Other services | 2024 |
| A1 Waste Solutions Limited | Professional & scientific | 2015 |
| A10 Drainage Services Ltd | Administrative & support | 2024 |
| A10 Mobility Ltd. | Manufacturing | 2016 |
| A11 Event Cleaners Ltd | Administrative & support | 2026 |
| A1KUTZ Ltd | Manufacturing | 2025 |
| A2 Real Estate Ltd | Real estate | 2025 |
| A22HOMES Limited | Construction | 2026 |
| A2ACOM Ltd | Construction | 2016 |
| A2B (East Herts) Ltd | Transport & logistics | 2021 |
| A2B (Herts) Limited | Transport & logistics | 2010 |
| A2BIC Ltd | Information & communication | 2025 |
| A2S Electrics Ltd | Manufacturing | 2025 |
| A7ASHER Ltd | Extraterritorial | 2022 |
| AA Assessments Ltd | Education | 2021 |
| AA FAN Experts Ltd | Administrative & support | 2020 |
| AA London Investments Ltd | Construction | 2022 |
| AA Properties (UK) Ltd | Real estate | 2013 |
| AA Real Estate Ltd | Real estate | 2020 |
| AAA Bespoke Services for Family Ltd | Administrative & support | 2025 |
| AAA Lukaj Ltd | Real estate | 2024 |
| Aaaristo Group Ltd | Wholesale & retail | 2015 |
| AAB Accountancy Ltd | Professional & scientific | 2011 |
| Aabkan Property Ltd | Real estate | 2025 |
| AAC (SP) Limited | Financial services | 2017 |
| AAC (ST) Limited | Financial services | 2017 |
| AAC Aircon Limited | Construction | 2013 |
| Aaccess Investments Ltd | Real estate | 2022 |
| Aace Property Management Ltd | Real estate | 2025 |
| Aada Holding Limited | Financial services | 2026 |
| AAG Developments Limited | Construction | 2019 |
| Aags Accountants Ltd | Professional & scientific | 2019 |
| Aamaroca Ltd | Other services | 2024 |
| Aamg Professional Services Ltd | Professional & scientific | 2023 |
| AAN Properties Ltd | Real estate | 2017 |
| Aaryaved Ltd | Professional & scientific | 2021 |
| Aasasa Ltd | Wholesale & retail | 2015 |
| Aask Ventures Ltd | Education | 2021 |
| Aask Watford Ltd | Education | 2023 |
| Aassed Property Limited | Real estate | 2024 |
| AB Bluestar Ltd | Other services | 2024 |
| AB Branding Ltd | Other services | 2018 |
| AB Education Services Ltd | Administrative & support | 2025 |
| AB Notaries Limited | Professional & scientific | 2023 |
| AB Published Limited | Information & communication | 2025 |
| ABA Drafting and Modelling Services Ltd | Professional & scientific | 2022 |
| Abaco Flooring Solutions Limited | Wholesale & retail | 2012 |
| Abajur Ltd | Professional & scientific | 2022 |
| Abbey Cafe Ltd | Hospitality | 2018 |
| Abbey Road Group Limited | Administrative & support | 2025 |
| Abbotts Mechanical and Electrical Ltd | Manufacturing | 2007 |
| ABC Customs Limited | Transport & logistics | 2018 |
| ABC Transportation Limited | Transport & logistics | 2025 |
| ABC Travel (Harlow) Limited | Transport & logistics | 2012 |
| Abcv Creative Signs Limited | Administrative & support | 2011 |
| Abdirahman Tutors Limited | Education | 2025 |
| Abefe's Catering Services Limited | Hospitality | 2024 |
| Abel GET 1884 Ltd | Construction | 2025 |
| Abel Search Ltd | Professional & scientific | 2018 |
| Abelite Consulting Limited | Professional & scientific | 2006 |
| Aberford Restaurant Ltd | Hospitality | 2020 |
| ABF Consulting Limited | Real estate | 2022 |
| ABI Consulting PVT Limited | Professional & scientific | 2014 |
| Abil Ltd | Other services | 2020 |
| Ability Holdings Ltd | Financial services | 2025 |
| Ability Payroll Ltd | Professional & scientific | 2025 |
| Ability Tax Advisory Ltd | Professional & scientific | 2025 |
| Ableline Limited | Extraterritorial | 2012 |
| ABO 02 Ltd | Other services | 2026 |
| Abritech Ltd | Manufacturing | 2003 |
| ABS Construct Ltd | Construction | 2026 |
| ABS Legal Support Services Limited | Administrative & support | 2020 |
| Absolute Heating Ltd | Other services | 2017 |
| Abstract Interior Solutions Ltd | Manufacturing | 2023 |
| ABT Imports and Exports Trading Co Limited | Manufacturing | 2024 |
| Abubax and Co Ltd | Construction | 2026 |
| ABZ Connect Ltd | Construction | 2026 |
| ABZ Valeting Ltd | Wholesale & retail | 2018 |
| AC Coaching Services Ltd | Education | 2025 |
| AC Electrical&Telecoms Ltd | Construction | 2025 |
| AC London Property Ltd | Real estate | 2020 |
| AC Private Vehicle Hire Services Ltd | Transport & logistics | 2026 |
| Ac.Comfort Ltd | Real estate | 2026 |
| Academia AI Limited | Information & communication | 2025 |
| Academia Angels Ltd | Education | 2024 |
| Acapella Academy Ltd | Wholesale & retail | 2021 |
| Acar Brothers Limited | Construction | 2013 |
| Accessory Shop Ltd | Wholesale & retail | 2017 |
| Accesssky Ltd | Construction | 2020 |
| Accordcare Management Limited | Administrative & support | 2020 |
| Accounts Zone Ltd | Professional & scientific | 2021 |
| Accoy Solutions PVT Ltd | Professional & scientific | 2024 |
| Ace Autos Ltd | Professional & scientific | 2019 |
| Ace Kebab Centre Limited | Hospitality | 2025 |
| Ace Medical Care Limited | Health & social care | 2020 |