| Alto Marketing Limited | Fareham | 2002 |
| Alto Markets Ltd | London | 2025 |
| Alto Media Group Limited | London | 2022 |
| Alto Nominees Limited | Essex | 1992 |
| Alto Secretaries Limited | London | 1994 |
| Alto Space Ltd | London | 2025 |
| Alto Systems Holdings Limited | Birmingham | 1987 |
| Alto Venture Ltd | Eastleigh | 2024 |
| Alto Verde Limited | Leicester | 2018 |
| Altoarch Limited | Gerrards Cross | 1989 |
| Altocloud Limited | Kidlington | 2009 |
| Altocrest Advisory Limited | Bolton | 2024 |
| Altodigital Networks Limited | Uxbridge | 2017 |
| Altofocus Limited | Wilmslow | 2015 |
| Altogether Care - Care Homes Limited | Dorset | 1996 |
| Altogether Care - Contract Management Ltd | Dorchester | 2021 |
| Altogether Compliant Ltd | Swindon | 2015 |
| Altogether Creative Ltd | Cramlington | 2016 |
| Altogether Different Ltd | Croydon | 2016 |
| Altogether NOW Limited | London | 2025 |
| Altogether Otherwise Limited | Manchester | 2023 |
| Altology Limited | Over Wallop | 2015 |
| Altomar Accountancy Limited | Poole | 2013 |
| Altomax Limited | London | 2025 |
| Altombros Ltd | London | 2020 |
| Altomex Limited | Bessacarr | 2013 |
| Altomics Datamation Limited | Belfast | 2020 |
| Alton & Co. Limited | London | 1998 |
| Alton Accountancy and Tax Limited | Stoke-On-Trent | 2024 |
| Alton Aviation Consultancy UK Limited | London | 2026 |
| Alton Creative Ltd | Bromsgrove | 2024 |
| Alton Detailing Limited | Chesterfield | 2007 |
| Alton Glasshouses Limited | Elland | 2010 |
| Alton House Finance Limited | Cobham | 1971 |
| Alton Management Ltd | London | 2023 |
| Alton Marketing Ltd | Twickenham | 2025 |
| Alton Pump Services Ltd | Southport | 2018 |
| Alton Secretarial Services Limited | London | 2000 |
| Alton Towers Limited | London | 1990 |
| Alton VETS4PETS Limited | Handforth | 2015 |
| Altona Diagnostics UK Limited | Liverpool | 2017 |
| Altona Surveying Ltd | Belfast | 2026 |
| Altonia Ltd | London | 2021 |
| Altonian Business Consultants Limited | Alton | 2026 |
| Altonis Investments Ltd | Galashiels | 2021 |
| Altonovus Limited | Farnham | 2015 |
| Altonwood Holdings Limited | Godstone | 1998 |
| Altor Employment Solicitors Limited | Milton Keynes | 2019 |
| Altor Fire Limited | York | 2013 |
| Altoran Access Services Limited | Liverpool | 2021 |
| Altorey Limited | Windsor | 2013 |
| Altorian Financial Management Limited | Manningtree | 2002 |
| Altoriax Ltd | London | 2026 |
| Altoriva Limited | Exeter | 2016 |
| Altos Advisory Ltd | London | 2026 |
| Altos Labs UK Limited | Altrincham | 2021 |
| Altos Ventures Ltd | London | 2025 |
| Altosync Ltd | London | 2024 |
| Altou M Ltd | London | 2026 |
| Altovara Consulting Limited | Bedford | 2026 |
| Altpex Consultancy Services Ltd | Newcastle Upon Tyne | 2026 |
| Altpin Ltd | Salford | 2020 |
| Altplan Holdings Limited | Staffordshire | 2002 |
| Altpro Insight Ltd | London | 2024 |
| Altprocure Ltd | Peterborough | 2025 |
| Altr Impact Community Interest Company | Burnley | 2024 |
| Altra Capital Limited | Ashford | 2007 |
| Altra Concept Ltd | Manchester | 2024 |
| Altra Energy Limited | St. Albans | 2020 |
| Altra Industrial Motion UK Holding Limited | London | 1999 |
| Altra Industrial Motion UK Limited | London | 1995 |
| Altra Solutions Ltd | Cambridge | 2025 |
| Altra Verba Ltd | Erith | 2025 |
| Altrad Beaver 84 Limited | Oldbury | 1984 |
| Altrad TS Holdings Limited | Aberdeen | 2011 |
| Altrad UK Limited | Warrington | 2017 |
| Altradez Property Services Ltd | Benfleet | 2021 |
| Altrain Ltd. | Johnstone | 2004 |
| Altralaw Ltd | Caerphilly | 2018 |
| Altram Solutions Limited | Enfield | 2015 |
| Altran UK Holding Limited | London | 1995 |
| Altran UK Limited | London | 1997 |
| Altrasky Limited | Leamington Spa | 2003 |
| Altrasoft Limited | Camberley | 1992 |
| Altrata Limited | London | 2003 |
| Altrata One Limited | Buckhurst Hill | 2013 |
| Altravista Design Studio Ltd | London | 2025 |
| Altray Consultancy Ltd | Slough | 2016 |
| Altree Ltd | Newport | 2021 |
| Altretire Limited | Chatham | 2018 |
| Altrex Engineering Ltd | Cambridge | 2022 |
| Altrica Ltd | Rugby | 2022 |
| Altries Developments Limited | Aberdeen | 2010 |
| Altrieve Accountancy Limited | Selkirk | 2013 |
| Altrieve Taxation Limited | Selkirk | 2014 |
| Altrincham Basement and Cellar Conversions Limited | Manchester | 2009 |
| Altrincham Business Change Limited | Altrincham | 2017 |
| Altrincham Finance Limited | Altrincham | 2017 |
| Altrincham Holdings Ltd | Altrincham | 2021 |
| Altrincham in Bloom C.I.C. | Altrincham | 2017 |