| Alresford Studios Ltd | Alresford | 2020 |
| Alresford Town FC Limited | Southampton | 2020 |
| Alright Mate? CIC | Exeter | 2019 |
| ALS Marketing Solutions Limited | Brierley Hill | 2016 |
| Alsager Bowling and Recreation Club Company Limited | Via Stoke On Trent | 1904 |
| Alsager Golf & Country Club (1992) Limited | Stoke On Trent | 1992 |
| Alsager Town Football Club Limited | Alsager | 2024 |
| Alscelar Golf Ltd | Devizes | 2023 |
| Alsignatureworks Ltd | London | 2025 |
| Alsinclair Holdings Limited | Birmingham | 2016 |
| Also Festival Ltd. | London | 2014 |
| Also This Limited | Estate Gateshead | 1995 |
| Also, There's Ghosts Limited | Swindon | 2024 |
| Also-H Productions Limited | Lymington | 2025 |
| Alstock Music Festival Ltd | Bodmin | 2020 |
| Alston Moor Fitness Club Limited | Alston | 2003 |
| Alston Work Studio Ltd | Barnet | 2023 |
| ALT Baile Ltd | London | 2026 |
| ALT Event Services Ltd | Falkirk | 2026 |
| ALT Fitness Ltd | Glasgow | 2019 |
| ALT K Dance Limited | Rugby | 2018 |
| ALT Management Ltd | Glasgow | 2020 |
| ALT Space Studio Limited | Whitchurch | 2022 |
| ALT. Productions Ltd | London | 2023 |
| Alta Loma Mgmt Ltd | London | 2008 |
| Alta LUX Ltd | London | 2022 |
| Alta Ritual Ltd | Redditch | 2021 |
| Alta Vita Events Ltd | Blackpool | 2024 |
| Alta Zenith Fitness Ltd | York | 2025 |
| Altair Aviation Limited | Chelmsford | 2003 |
| Altair Live Limited | Ventnor | 2026 |
| Altair Velin Studios Limited | London | 2024 |
| ALTAIR12 Ltd | London | 2021 |
| Altala Group Ltd | London | 2007 |
| Altar Fitness Ltd | Ellesmere | 2025 |
| Altares Group Ltd | London | 2025 |
| Altay Technology Ltd | Ashford | 2025 |
| Altbet Limited | Banbury | 2014 |
| Altd Productions Ltd | Preston | 2025 |
| Alter Rock Limited | Derbyshire | 2008 |
| Alter-Ego Athletic Limitless Projects CIC | Peterborough | 2025 |
| Alteration Services Limited | London | 2015 |
| Alterean Media Limited | Wallasey | 2013 |
| Altered Image Gymnasium Ltd | Leeds | 2018 |
| Altered Skin CIC | Birmingham | 2019 |
| Altered State Talks Ltd | Chepstow | 2023 |
| Alterego Creative Solutions Ltd | Northampton | 2012 |
| Alternate Reality, Ltd. | London | 2023 |
| Alternative Experiences UK Limited | Newry | 2025 |
| Alternative Fitness Solutions Ltd | Andover | 2008 |
| Alternative Hair Ltd. | Hertfordshire | 1998 |
| Alternative History Haunted Tours Limited | Haddington | 2025 |
| Alternative Music & Events Company Limited | Gloucestershire | 2004 |
| Alternative Narratives Ltd | Clevedon | 2025 |
| Alternative Stories Ltd | Oakham | 2022 |
| Alternative Sussex Weddings Ltd | Sutton | 2025 |
| Alternative Theatre Company Limited | London | 1975 |
| Alternatively Healthy London Limited | Congleton | 2015 |
| Altesc Ltd | Lisburn | 2017 |
| Altin Halil Limited | London | 2012 |
| Altira Yachting Ltd | London | 2024 |
| Altissimo Music Limited | | 1991 |
| Altitude Comedy Festival Limited | Wallasey | 2019 |
| Altitude Cornwall Ltd | Cornwall | 2021 |
| Altitude Events Limited | East Grinstead | 2012 |
| Altitude Lighting Limited | Harrow | 2026 |
| Altitude Specialist Contracting Limited | Castel Marina | 1991 |
| Altitude Tattoo Limited | Doncaster | 2019 |
| Altitude Trampoline Club Ltd | Colchester | 2025 |
| Altitude Ventures Ltd | Hitchin | 2026 |
| Altitude Wombles TV Limited | London | 2019 |
| Altius Gymnastics Ltd | Liverpool | 2025 |
| Altius PT Limited | Northampton | 2018 |
| Altiville Ltd | Corby | 2023 |
| Alto Grye Ltd | London | 2017 |
| Alto One Limited | Liverpool | 2024 |
| Altofts Community and Sports Foundation Limited | Wakefield | 2011 |
| Altofts CUT Private Moorings Limited | Castleford | 2012 |
| Altogether Entertainment Limited | Nottingham | 2024 |
| Altomyra Limited | Abingdon | 2020 |
| Alton (Hants) Rifle Club Limited | Farringdon | 2016 |
| Alton Arts Festival CIC | Alton | 2023 |
| Alton Brewing Heritage Trail CIC | Alton | 2024 |
| Alton Cricket Club C.I.C. | Alton | 2025 |
| Alton Martial Arts Academy Ltd | Farnborough | 2018 |
| Alton Piece Equestrian Centre Limited | Brierley Hill | 2019 |
| Alton Towers Resort Operations Limited | London | 2007 |
| Altramart Limited | Chelmsford | 2016 |
| Altrincham & District Athletic Club Limited | Altrincham | 2015 |
| Altrincham Aces Ice Hockey Club Ltd | Lymm | 2018 |
| Altrincham Association Football Club,Limited | Altrincham | 1921 |
| Altrincham Escape Ltd | Altrincham | 2024 |
| Altrincham Fitness Ltd | Liverpool | 2019 |
| Altrincham Football Club Community Sports Limited | Altrincham | 2012 |
| Altrincham Garrick Playhouse,Limited | Cheshire | 1931 |
| Altrincham Garrick Society Limited | Altrincham | 1994 |
| Altrincham Ice Hockey Club Limited | Bolton | 2015 |
| Altripp Design Management Limited | Wallington | 2012 |
| Altro Estudio Limited | Glasgow | 2024 |
| Altruviolet (Traplord) Ltd | London | 2021 |