| Alchemy Automation Ltd | Heathfield | 2015 |
| Alchemy Fabrics Ltd | Wilmslow | 2023 |
| Alchemy Pictures Limited | Louth | 2003 |
| Alco Sachet Limited | Henley-On-Thames | 2004 |
| Alcoa Aluminum Ltd | Manchester | 2019 |
| Alcohol and Drug Abstinence Service (Management) Limited | Burnley | 2008 |
| Alcohol Aware Limited | Wigan | 2018 |
| Alcohol UN Limited | Swansea | 2023 |
| Alcoholic Beverage Ventures Ltd | Tonbridge | 2021 |
| Alcourt CIC | Southsea | 2020 |
| Alcrafield Limited | Slaithwaite | 1968 |
| Alcuin Homes (Yorkshire) Holdings Limited | York | 2015 |
| Alcuin Homes Holdings Limited | Wakefield | 2015 |
| Alcyon Management Ltd | Bedford | 2016 |
| Alcyonis Maritime Limited | Cardiff | 2018 |
| ALD (Redhills) Ltd | Exeter | 2023 |
| ALD Lighting Solutions Limited | Pevensey Bay | 2020 |
| Aldane Limited | Cambridge | 2022 |
| Aldbrough Caravan Park Limited | Bridlington | 2008 |
| Aldburgh Estate Company Limited | Leeds | 2018 |
| Aldcrofts Limited | Bolton | 2013 |
| Aldea Bella (Number 215) Limited | Glasgow | 1984 |
| Aldeburgh Consultancy Ltd | Aldeburgh | 2020 |
| Aldeburgh Hotels Limited | Leiston | 1997 |
| Aldeburgh Music Limited | Saxmundham | 1987 |
| Aldeburgh Water Ltd | London | 2020 |
| Aldenham Aviation 2 Limited | Herts | 2023 |
| Aldens Restaurant Limited | Belfast | 1985 |
| Alder & Finch Group Ltd | Doncaster | 2026 |
| Alder Holdings Limited | Dunoon | 2017 |
| Alder MAY Limited | Cheltenham | 2014 |
| Alder Miles Druce Limited | Birmingham | 1947 |
| Alder Point Consulting Firm Ltd | Manchester | 2026 |
| Alder-Diels (UK) Ltd | Beckenham | 2016 |
| Alderfen Yacht and Marine Surveys Ltd | Norwich | 2021 |
| Alderley Edge Hockey Club Ltd | Wilmslow | 2013 |
| Alderley Edge Squash Club Limited | Wilmslow | 2014 |
| Alderley Edge Tennis Club Limited | Wilmslow | 2014 |
| Alderley GIN Ltd | Nether Alderley | 2019 |
| Alderley&Co Properties Ltd | Stockport | 2024 |
| Aldermartin Ltd | Edgware | 2016 |
| Aldermore Invoice Finance (Holdings) Limited | Reading | 2009 |
| Aldermore Invoice Finance (Oxford) Limited | Reading | 1987 |
| Aldermore Invoice Finance Limited | Reading | 1990 |
| Aldern Way 1972 Limited | Bakewell | 2013 |
| Alderney Learning and Development Ltd | Manchester | 2015 |
| Alderock Limited | Belfast | 2012 |
| Aldersgate Probate Ltd | London | 2020 |
| Aldershot Car Spares Limited | Loughton | 2010 |
| Alderson Investco Limited | Harrogate | 2021 |
| Alderview Limited | Edinburgh | 2002 |
| Alderwey Limited | Sevenoaks | 2008 |
| Alderwood Medical Practice GPF Limited | Cannock | 2018 |
| Aldford Street Nominees Limited | Weybridge | 2007 |
| Aldia (Holdings) Limited | Hampton | 2012 |
| Aldimashqi (Kensington) Ltd | London | 2021 |
| Aldomann (Clydebank) Ltd | East Kilbride | 2016 |
| Aldon Construction Company Limited | Blackpool | 1956 |
| Aldon Solutions Limited | London | 2011 |
| Aldrene Gargett Ltd | Kington | 2021 |
| Aldrene Heather Gargett Ltd | Kington | 2024 |
| Aldridge Accountants Limited | Trowbridge | 2014 |
| Aldridge Projects Limited | Lytham St. Annes | 2022 |
| Aldridge Trimming EOT Limited | Wolverhampton | 2021 |
| Aldryx Group Ltd | Doncaster | 2026 |
| Aldway Eleven Limited | London | 1919 |
| Aldway Stamping Ltd | Worthing | 1912 |
| Aldwych Art Finance Ltd | London | 2025 |
| Aldwych Limited | Portadown | 2013 |
| Aldwych Logistics Investments Limited | London | 2010 |
| Aldybry Concept Invest Ltd | Dover | 2023 |
| Aldybry Concept Ltd | Dover | 2023 |
| ALE Festival UK Ltd | Beverley | 2012 |
| Aleaas Ltd | London | 2025 |
| Alebrije Consulting Ltd | Reading | 2020 |
| Alebrije Management, Ltd | London | 2019 |
| Alec Brennand Limited | Ashton-Under-Lyne | 2009 |
| Alec French Architects Limited | Bristol | 2005 |
| Alecto Electrical and Building Contractors Limited | Consett | 2021 |
| Aled Investment Sweden Limited | London | 2023 |
| Aled Rhys Consultancy Limited | Loughborough | 2019 |
| Aled Sweden Limited | London | 2023 |
| Alee Trading Co., Ltd | London | 2012 |
| Aleel Management Limited | Croydon | 2020 |
| Alegio Limited | Dumfries | 2022 |
| Alegria Counselling Ltd | Berkhamsted | 2024 |
| Alegria Wellbeing Services Ltd | Berkhamsted | 2024 |
| Alegup.Co.Uk Ltd | Chelmsford | 2021 |
| Aleida Ltd | London | 2025 |
| Aleka Management Limited | London | 2011 |
| Alekis Building Company Limited | Pencoed, Bridgend | 2009 |
| Aleks Motorman Engineering Ltd | Milton Keynes | 2024 |
| Aleksandar Ljusic Limited | London | 2019 |
| Aleksanders Borodins Ltd | Northampton | 2023 |
| Aleksandra Bryzgina Ltd | London | 2025 |
| Aleksandra Dominic Consulting Limited | London | 2017 |
| Alembic Foods Limited | Liverpool | 2004 |
| Alen Marine Ltd | Blackpool | 2024 |
| Aleph Capital Limited | London | 2015 |
| Aleph Limited | London | 2016 |