| Amplify Songs 138 Limited | Arts & recreation | 2013 |
| Amplify Songs 139 Limited | Arts & recreation | 2013 |
| Amplify Songs 141 Limited | Arts & recreation | 2014 |
| Amplify Songs 142 Limited | Arts & recreation | 2014 |
| Amplify Songs 143 Limited | Arts & recreation | 2014 |
| Amplify Songs 144 Limited | Arts & recreation | 2014 |
| Amplify Songs 145 Limited | Arts & recreation | 2014 |
| Amplify Songs 161 Limited | Arts & recreation | 2016 |
| Amplify Songs 162 Limited | Arts & recreation | 2016 |
| Amplify Songs 163 Limited | Arts & recreation | 2016 |
| Amplify Songs 164 Limited | Arts & recreation | 2016 |
| Amplify Songs 165 Limited | Arts & recreation | 2016 |
| Ampshire Property Ltd | Real estate | 2024 |
| AMR Heating & Plumbing Services Ltd | Construction | 2017 |
| AMR Property Maintenance Ltd | Administrative & support | 2018 |
| Amritsari Momo Limited | Hospitality | 2025 |
| Amro Business Services Ltd | Administrative & support | 2017 |
| Amrock Developments Company Limited | Construction | 2024 |
| Amrock Holdings UK Limited | Financial services | 2024 |
| AMS 2280 Limited | Information & communication | 2005 |
| AMS 4 Consulting Ltd | Professional & scientific | 2019 |
| AMS Bristol Ltd | Construction | 2023 |
| AMS Capital Property Limited | Real estate | 2026 |
| AMS Educational Limited | Professional & scientific | 2006 |
| Amsa Services Ltd | Education | 2024 |
| Amschela Ltd | Wholesale & retail | 2016 |
| Amshaykh Co Ltd | Wholesale & retail | 2026 |
| Amsher Ltd | Administrative & support | 2007 |
| Amsj Holdings Ltd | Health & social care | 2025 |
| Amtoll Limited | Wholesale & retail | 1989 |
| Amusements Limited | Arts & recreation | 1981 |
| AMV Consulting Limited | Professional & scientific | 2019 |
| AMW Heating Ltd | Construction | 2021 |
| AMY Flooring Ltd | Construction | 2016 |
| AMY Louise Communications Ltd | Arts & recreation | 2024 |
| AMY Moorea Wong Limited | Professional & scientific | 2021 |
| AMY Nails Bristol Ltd | Other services | 2025 |
| AMY Nails BS35 Ltd | Other services | 2024 |
| AMY Snowdon Limited | Professional & scientific | 2023 |
| AMY Sweet Limited | Professional & scientific | 2025 |
| AMY Treasure Media Limited | Professional & scientific | 2022 |
| AMY Wheldrake Ltd | Construction | 2025 |
| Amy's Thai Fusion Cuisine Ltd | Hospitality | 2025 |
| Amyb Ltd | Information & communication | 2023 |
| Amyntas Associates Limited | Information & communication | 1996 |
| AMZ Hena MUA Ltd | Administrative & support | 2015 |
| Amzeagles Ltd | Wholesale & retail | 2023 |
| Amzocart Ltd | Wholesale & retail | 2024 |
| AN Advisory Partners Ltd | Professional & scientific | 2026 |
| AN Alternative Perspective Ltd | Extraterritorial | 2023 |
| AN Beauty Limited | Other services | 2025 |
| AN Discount Store Ltd | Wholesale & retail | 2020 |
| AN Electrical Services Ltd | Construction | 2018 |
| AN Exploration of Self Ltd | Extraterritorial | 2023 |
| ANA Maria Salazar Consultancy Services Ltd | Professional & scientific | 2025 |
| ANA Quintanilla Limited | Health & social care | 2023 |
| Anabiel Limited | Health & social care | 2026 |
| Anaesthetsia Education Group Ltd | Other services | 2024 |
| Anagen Innovation Medicine Ltd | Manufacturing | 2024 |
| Anago Software Ltd | Information & communication | 2024 |
| Anajapi Homes Ltd | Real estate | 2020 |
| Anakin Real Estate Limited | Real estate | 2025 |
| Analog Developments Limited | Manufacturing | 2006 |
| Analogue Holdings Limited | Information & communication | 2026 |
| Analogue Pigeon Limited | Information & communication | 2026 |
| Analogue Spirits Ltd | Wholesale & retail | 2011 |
| Analogue Ventures Ltd | Professional & scientific | 2023 |
| Analysis Squared Limited | Information & communication | 2012 |
| Analytics 2I Ltd | Information & communication | 2015 |
| Analytics Business Console Limited | Information & communication | 2009 |
| Anamaria Healthcare Services Ltd | Health & social care | 2018 |
| Ananda Greens Ltd | Agriculture & fishing | 2025 |
| Ananda Investments Limited | Real estate | 2016 |
| Anaphite Limited | Manufacturing | 2016 |
| Anaplan Limited | Information & communication | 2007 |
| Anatolia UK Limited | Wholesale & retail | 2012 |
| Anatrey Care Ltd | Other services | 2022 |
| Anavi Consulting Ltd | Education | 2011 |
| Anavpa Ltd | Information & communication | 2023 |
| Anavrin Holdings Limited | Other services | 2016 |
| Anaya Offices Ltd | Real estate | 2025 |
| Anayah Private Ltd | Wholesale & retail | 2020 |
| Anchor & Atlas Ltd | Administrative & support | 2025 |
| Anchor 1881 Ltd | Hospitality | 2023 |
| Anchor Community Childrens Services Ltd | Health & social care | 2025 |
| Anchor Community Support Ltd | Health & social care | 2021 |
| Anchor Day Nursery Limited | Health & social care | 2017 |
| Anchor Road Management Company Limited | Households | 2024 |
| Anchor Stores Limited | Wholesale & retail | 2022 |
| Anchor'D Estates Ltd | Real estate | 2023 |
| Anchorage Residential Properties Limited | Real estate | 2019 |
| Anco Divers Limited | Arts & recreation | 2008 |
| Anco Storage Equipment Limited | Construction | 1997 |
| AND Brands Ltd | Wholesale & retail | 2023 |
| AND Keep Limited | Wholesale & retail | 2016 |
| AND Still the Bells Productions Ltd | Information & communication | 2025 |
| AND the Family Ltd | Professional & scientific | 2022 |
| Anda Cleaning Ltd | Administrative & support | 2025 |
| Andaman Residential Ltd | Health & social care | 2025 |
| Andan Transport Ltd | Transport & logistics | 2014 |