| Amtrak Limited | Walsall | 2007 |
| Amtre Veritas Standard Technical Testing Ltd | Beckenham | 2018 |
| AMU Construction Ltd | Surbiton | 2025 |
| Amuka Limited | Solihull | 2014 |
| Amulet 1959 Limited | Wells | 2015 |
| Amuno Developments Limited | Bournemouth | 2013 |
| Amura 7 Ltd | London | 2021 |
| Amusement Rides and Automatics Limited | London | 1957 |
| AMV Law Group Ltd | Brighton | 2017 |
| Amvis Limited | London | 2011 |
| AMW Electrical Limited | Bridgnorth | 2008 |
| Amwm Groundworks Ltd | Thetford | 2023 |
| AMX Capital Ltd | London | 2023 |
| AMY Beth Dalla Mura Ltd | Hove | 2024 |
| AMY Louise Burford Ltd | Gillingham | 2023 |
| AMY Morwenna Grove Limited | Louth | 2024 |
| Amyris Limited | Harlow | 1993 |
| AMZ Hustles Ltd | Normanton | 2022 |
| Amzbarley Trading Co., Ltd | Cambridge | 2019 |
| AN (123) Limited | London | 1898 |
| AN Alternative Perspective Ltd | Bristol | 2023 |
| AN Amplified Life Ltd | Nottingham | 2024 |
| AN Avel Braz Real Estate Limited | London | 2006 |
| AN Englishrose Limited | Maidstone | 2013 |
| AN Exploration of Self Ltd | Bristol | 2023 |
| AN in the Sea Limited | London | 2023 |
| AN Ltd | Saffron Walden | 2009 |
| AN Tairbeart Limited | Argyll | 1992 |
| AN Teallach Energy Company Ltd | Stornway | 2009 |
| An-Core Ltd | Kingston Upon Thames | 2009 |
| An-Li Tradings Limited | London | 2018 |
| AN1TA Ltd | Harrogate | 2020 |
| AN4 Networks Limited | Hampshire | 1994 |
| AN45 UK Ltd | Bucks | 2023 |
| ANA California Ltd | Manchester | 2010 |
| ANA Development Group Limited | Sutton Coldfield | 2021 |
| Anaanan Limited | Cardiff | 2009 |
| Anaash Holdings Limited | Barnet | 2008 |
| Anabata Limited | London | 2019 |
| Anabixus Ltd | London | 2015 |
| Anadi Ltd | Manchester | 2024 |
| Anaerobic Digestion Asset Maintenance (Adam) Limited | Bedford | 2023 |
| Anaesthesia Medical Services Ltd | Holywood | 2013 |
| Anahata Bodhisattva Ltd | Matlock | 2022 |
| Anaig (UK) Technology Co., Ltd | Kington | 2015 |
| Anakin Seal Legal Limited | London | 1993 |
| Analec Trustees Limited | Winchester | 2012 |
| Analog Pictures Limited | London | 2018 |
| Analog Sailing Ltd | London | 2025 |
| Analogue Ltd | London | 2022 |
| Analogue Solutions Limited | Barry | 1994 |
| Analyst Group Limited | Harrogate | 2025 |
| Analytic Business Consulting Limited | Southampton | 2009 |
| Analytic INT IT PLC | Dover | 2023 |
| Analytik Trustee Limited | Swavesey | 2026 |
| Analytiq Global Solutions Ltd | Ilford | 2020 |
| Anam Cara Aviation Limited | Banbury | 2010 |
| Anamsa Real Estate Limited | Harpenden | 2024 |
| Anand Green Ltd | Barnet | 2018 |
| Anantaa Private Ltd | Coventry | 2024 |
| Anas Eiendomsutvikling Limited | London | 2024 |
| ANASTAS1A Limited | Harrogate | 2020 |
| Anastasia Art Ltd | Newport | 2024 |
| Anastasia Limited | Blackpool | 2025 |
| Anastasia M Yachting Limited | London | 2016 |
| Anastasia Mews Management Limited | Barnet | 2012 |
| Anathema Emporium Ltd | Bournemouth | 2026 |
| Anatolia Yachting Ltd | London | 2025 |
| Anatomiq Ltd | Liskeard | 2026 |
| Anatta Barakah Ltd | London | 2026 |
| Anaya Global Mart Limited | London | 2023 |
| ANB Consultancy Ltd | London | 2020 |
| Anbil Limited | Exeter | 2010 |
| Anca Consulting Ltd | London | 2013 |
| Anca Tapes Limited | Halesowen | 1997 |
| Ancala Water Services Bidco Limited | Barnsley | 2017 |
| Ancala Water Services Investco Limited | London | 2017 |
| Ancala Water Services MIDCO1 Limited | London | 2017 |
| Ancala Water Services MIDCO2 Limited | London | 2017 |
| Ancala Water Services Topco Limited | London | 2017 |
| Ancaro Limited | Chester | 2023 |
| Ancasterdirect Limited | Bruton | 2013 |
| Ancestra Limited | Dorchester | 2025 |
| Ancestral Homes Limited | Cobham | 1996 |
| Anchor & Hope IT Solutions Ltd | Ellesmere Port | 2019 |
| Anchor Bay Construction Products Limited | London | 2017 |
| Anchor Bay Products Limited | Ipswich | 2024 |
| Anchor Catering (Plymouth) Limited | Plymouth | 2022 |
| Anchor for Investment Limited | Manchester | 2026 |
| Anchor GR Limited | London | 2017 |
| Anchor Magnets Limited | Sheffield | 1998 |
| Anchor Marine Ltd | London | 2025 |
| Anchor OIL Company Limited | Londonderry | 1995 |
| Anchor Park the Garden Village Ltd | Norfolk | 2020 |
| Anchor Star Ltd | Shepherds Bush | 2010 |
| Anchor Systems (Europe) Limited | Lingfield | 2014 |
| Anchor Systems Limited | Lingfield | 2015 |
| Anchor-Uk Ltd | Waterlooville | 2026 |
| Anchorage Automotive Engineering Services Limited | Leamington Spa | 2017 |
| Anchoring International Limited | Cradley Heath | 1992 |