| Aldershot and Fleet Rugby Union Football Club Limited | Aldershot | 2011 |
| Aldershot Contemporary CIC | Farnham | 2025 |
| Aldershot Town Football Club Limited | Aldershot | 2013 |
| Alderton Trading Limited | London | 2025 |
| Alderville Consulting Limited | Exeter | 2020 |
| Alderwood Shoot Ltd | Belfast | 2018 |
| Alderworks Ltd | Seaford | 2014 |
| Alderzone Limited | Herts | 1985 |
| Aldon Eventing Limited | Beaminster | 2014 |
| Aldoonia Limited | London | 2011 |
| Aldred Sports Management Limited | Wakefield | 2015 |
| Aldridge Personal Training Ltd | Sutton Coldfield | 2019 |
| Aldridge Rugby Football Club Limited | Walsall | 2010 |
| Aldwick Services Limited | Chichester | 2018 |
| Aldwinter Limited | London | 2017 |
| Aleatory Objects Limited | London | 2020 |
| Alec Doherty Ltd | London | 2021 |
| Alec Gordon Productions Limited | Newcastle Upon Tyne | 2018 |
| Alec Lochore Event & Equestrian Consultancy Ltd. | King'S Lynn | 2014 |
| Alec Reed Academy Enterprise Limited | Northolt | 2011 |
| Alecto Collective Limited | Cardiff | 2025 |
| Aled Jones Enterprises Limited | London | 1988 |
| Aled Lewis Studio Ltd | Alton | 2012 |
| Alees Services UK Limited | Surrey | 2019 |
| Alegria Entertainment Ltd | Glasgow | 2025 |
| Alejandra Patterns Ltd | London | 2026 |
| Aleksandra Masalska Conservation Ltd | London | 2021 |
| Aleksandra Niemczyk Art Ltd | London | 2021 |
| Aleksvediani Ltd | Barnet | 2026 |
| Alela Events Ltd | London | 2026 |
| Alem Ltd | Alresford | 2021 |
| Alem Nightlife Limited | Chippenham | 2016 |
| Alento Collective Ltd | London | 2025 |
| Alep Ltd | Mildenhall | 2025 |
| Aleph Construction Engineering Ltd | London | 2020 |
| Aleph Libros Limited | London | 2018 |
| Alerion Strings Limited | London | 2023 |
| Alert Security Services Limited | Rayleigh | 1989 |
| Alessandra Tortone Ltd | London | 2018 |
| Alessandro DI Rosa Studios Ltd | London | 2023 |
| Alessandro Rabottini Limited | Waterlooville | 2022 |
| Alessio Helen Limited | Waltham Cross | 2019 |
| Alethoscope Media Ltd | North Shields | 2018 |
| Aleto Fitness Ltd | Bolton | 2023 |
| Aletrack Limited | Huddersfield | 2006 |
| Alex and Emma Devereux Ltd | London | 2021 |
| Alex and James ARE Dead Limited | Exmouth | 2021 |
| Alex AV Ltd | Leicester | 2024 |
| Alex Banks Music Ltd | Beccles | 2002 |
| Alex Bowron Art Limited | Southampton | 2024 |
| Alex Buckner Golf Ltd | Maidenhead | 2020 |
| Alex Caldwell Ltd | Erskine | 2026 |
| Alex Camacho Graphics Limited | St. Albans | 2013 |
| Alex Chadwick Consultancy Ltd | London | 2022 |
| Alex Chilton Design Limited | Southampton | 2006 |
| Alex Chinneck Limited | Ashford | 2015 |
| Alex Crow Limited | Windsor | 2004 |
| Alex Douglas Ltd | London | 2015 |
| Alex Duncan Racing Limited | Eaglesham | 2025 |
| Alex Graham Limited | London | 1985 |
| Alex Harvey Limited | London | 2025 |
| Alex Holman Ltd | Norwich | 2012 |
| Alex Holt Fitness Ltd | Northwich | 2024 |
| Alex Howell Consulting Ltd | Edinburgh | 2019 |
| Alex I Yachting Ltd | London | 2024 |
| Alex Iwobi Promotions Limited | London | 2016 |
| Alex James Coaching Ltd | Tonbridge | 2021 |
| Alex Jordan Limited | London | 2014 |
| Alex Jordan Performance Ltd | Worthing | 2025 |
| Alex Lanyon Limited | Harrow | 2024 |
| Alex Loveless Ltd | London | 2025 |
| Alex Lynn Racing Limited | Northampton | 2010 |
| Alex Macdonald Loyal Rangers Supporters Club Ltd | Belfast | 2025 |
| Alex Marwood Ltd | London | 2011 |
| Alex MAY Hughes Ltd | Farnborough | 2022 |
| Alex Mcgregor Costumes Limited | Chester | 2018 |
| Alex Minors Limited | Kings Langley | 2006 |
| Alex Morris Tennis Limited | Cobham | 2025 |
| Alex Murphy Production Lighting Ltd | London | 2021 |
| Alex Newsham Showjumping Limited | Tarporley | 2018 |
| Alex Oakley Ltd | London | 2015 |
| Alex Olsen Racing Ltd | Rochester | 2020 |
| Alex Pearson Productions Limited | Woodbridge | 2017 |
| Alex Promotions Limited | London | 2007 |
| Alex Reader Fitness Limited | Budleigh Salterton | 2025 |
| Alex Reynier Ltd | London | 2009 |
| Alex Selby Health & Fitness Ltd | Kenilworth | 2018 |
| Alex Stead Art Ltd | Sidcup | 2016 |
| Alex Treadway Limited | Malvern | 2015 |
| Alex Vass Ltd | Gloucester | 2021 |
| Alex Walker Personal Training Ltd | Stockport | 2023 |
| Alex Watson Animation Ltd | Birmingham | 2017 |
| Alex Wellesley Wesley Art & Design Limited | Slough | 2007 |
| Alex Williamson Illustration Limited | Bath | 2014 |
| Alex Woods Online Coach Ltd | Rotherham | 2022 |
| Alex YEE Limited | Ipswich | 2018 |
| Alex-Perry.Com Limited | Alton | 2014 |
| Alexander Adventures Ltd | London | 2019 |
| Alexander Alexander Ltd | Sidcup | 2018 |
| Alexander Arcoleo Ltd | Congleton | 2020 |