| Alto LAB Ltd | Brighton | 2016 |
| Alto Services Ltd | Buxton | 2018 |
| Altomedia Limited | London | 2008 |
| Alton Autos Ltd | Bristol | 2023 |
| Alton Business Centre Management Association Limited | Alton | 1990 |
| Alton Ocean Co., Ltd | Stafford, | 2014 |
| Alton Saint-Clair Limited | Harrogate | 2025 |
| Altra Property Investments Ltd | Cardiff | 2016 |
| Altram L.R.T. Limited | Birmingham | 1993 |
| Altrapoint Ltd | Hoddesdon | 2026 |
| Altries Services Limited | Aberdeen | 2010 |
| Altrin Limited | Colwyn Bay | 2012 |
| Altrincham Carpet & Suite Centre Limited | Liverpool | 1986 |
| Altrincham Day Nursery Limited | Liverpool | 2015 |
| Altrincham Flooring Limited | Altrincham | 2022 |
| Altrincham International Grammar School Limited | Macclesfield | 2016 |
| Altrofix Limited | Letchworth Garden City | 1980 |
| Altrosport Surfaces Limited | Letchworth Garden City | 1927 |
| Altruia Limited | Liphook | 2016 |
| Altum Precision E&I Ltd | Newry | 2019 |
| Altura Studios Ltd | London | 2013 |
| Alturo Management Limited | Poole | 2026 |
| Alturon for International Services Limited | Manchester | 2026 |
| Altus Learning UK Ltd | Hanwell | 2021 |
| Altvia Solutions Limited | Cheltenham | 2016 |
| Alu-Rail (Ireland) Limited | | 2003 |
| Alue Ltd | Bury St. Edmunds | 2024 |
| Aluframe Limited | Rackheath Norwich | 2018 |
| Aluke Machine Tool Co., Ltd | Beckenham | 2009 |
| Alula Asset Ltd | Charing | 2016 |
| Alula Limited | London | 2007 |
| Aluliving Ltd | Stamford | 2020 |
| Alumaflex Limited | Essex | 2004 |
| Aluman Glazing Accessories Limited | Newcastle Upon Tyne | 2014 |
| Alumasc Construction Products Limited | Kettering | 1947 |
| Alumasc D Developments Limited | Kettering | 1992 |
| Alumasc DD Limited | Kettering | 1919 |
| Alumasc Exterior Building Products Limited | Kettering | 1907 |
| Alumasc Holdings Limited | Kettering | 1917 |
| Alumasc Interior Building Products Limited | Kettering | 1999 |
| Alumasc Precision Limited | Kettering | 1999 |
| Alumasc-Grundy Limited | Kettering | 1929 |
| Aluminium Boat Company Ltd | Dartmouth | 2022 |
| Aluminium Extrusions Online Limited | Peacehaven | 2022 |
| Aluminium Gutters Ltd | Bournemouth | 2020 |
| Aluminium Profile Services Limited | Bingley | 2015 |
| Aluminium Zero Limited | London | 2021 |
| Alun Jones of Red Star Lofts Limited | Prestatyn | 2012 |
| Alunay Ltd | London | 2023 |
| Alupro Limited | Bromsgrove | 1998 |
| Alur 149382 Limited | London | 2022 |
| Aluroll Security Limited | Oswestry | 2022 |
| Alushred Limited | Bury St. Edmunds | 2006 |
| Alustrade Limited | Leeds | 2017 |
| Alutec Engineering Limited | Belfast | 2017 |
| Alutech Systems Limited | Gerrards Cross | 2022 |
| Alutur Heritage Doors Limited | Leicester | 2022 |
| Aluz Licence Co Ltd | London | 2024 |
| Aluzen Ltd | Leeds | 1999 |
| Alvard Snekkertjenester Invest Limited | London | 2021 |
| Alvard Snekkertjenester Limited | London | 2021 |
| Alvarez (UK) Ltd | Egham | 2005 |
| Alvaston Mobile Home Park Limited | London | 1966 |
| Alvechurch Boat Centres Limited | Worcestershire | 2007 |
| Alverra Holdings Ltd | Doncaster | 2026 |
| Alveston Healthcare Limited | Walsall | 2025 |
| Alvi Group Ltd | Manchester | 2025 |
| Alvinet Films Limited | Rossendale | 2013 |
| Alvis Pension Scheme Trustees Limited | Camberley | 2001 |
| Alvis Vickers Limited | Camberley | 1997 |
| Alvtex Enterprises Limited | Stevenage | 2014 |
| Alwa Limited | Broxbourne | 2023 |
| Alwahwood Limited | Uxbridge | 2022 |
| Alwalid Ltd | Edinburgh | 2023 |
| Always Apprentices Ltd | Shrewsbury | 2018 |
| Always Brit Ltd | Sutton | 2025 |
| Always Care Cornwall Ltd | Plymouth | 2017 |
| Always Fashion Jewelry Co., Limited | London | 2018 |
| Alwayson Business Limited | Newbury | 2013 |
| Alwaàn Ltd | Bristol | 2023 |
| Alwisam Import and Export Trading Co., Ltd | Beckenham | 2023 |
| ALX Holdings Limited | Bradford | 1992 |
| ALX Limited | London | 2008 |
| Alycidon Mews Management Company Limited | Newmarket | 2015 |
| Alyf Accountants Ltd | Coventry | 2021 |
| Alyse Marie Laing Limited | Pontyclun | 2025 |
| Alzanti Ltd | Ringwood | 2012 |
| AM & Sons Management Ltd | Liverpool | 2024 |
| AM Access Ltd | Stoke-On-Trent | 2010 |
| AM Consulting Global Limited | London | 2018 |
| AM Farms Limited | Trowbridge | 2023 |
| AM Financial Management Limited | Edinburgh | 2009 |
| AM Fire & Security Limited | London | 2016 |
| AM Fit Ltd | Epsom | 2017 |
| AM Hydraulics Engineering Services Limited | Birmingham | 2016 |
| AM Hydraulics Limited | Birmingham | 2016 |
| AM Innovation Consultancy Ltd | Woodford Green | 2013 |
| AM Insulation Limited | Ballyclare | 2023 |
| AM Investment Management Ltd | Edinburgh | 2012 |
| AM Lagonda (UK) Limited | Warwick | 2009 |