| A Study of Life LLP | | 2021 |
| A Style & Glow Studio Ltd | Other services | 2026 |
| A Suitable Company Limited | Information & communication | 2018 |
| A Summer in Ltd | Manufacturing | 2025 |
| A Summer's Portrait Films Ltd | Information & communication | 2026 |
| A Supreme Clean Ltd | Administrative & support | 2017 |
| A Surucu Limited | Real estate | 2014 |
| A Sustainable Department Store Limited | Wholesale & retail | 2019 |
| A Sustainable Way Limited | Information & communication | 2021 |
| A Swann Consulting Ltd | Professional & scientific | 2024 |
| A Sweetman Consulting Limited | Financial services | 2025 |
| A Swile Limited | Health & social care | 2016 |
| A SXC Imagination Ltd | Wholesale & retail | 2025 |
| A SY Solutions Ltd | Information & communication | 2021 |
| A System Ltd | Construction | 2014 |
| A T & C Audio Technology & Communications Limited | Other services | 1991 |
| A T & C Professional Systems Limited | Other services | 2009 |
| A T a Sunrays Limited | Professional & scientific | 2006 |
| A T Best Ventures Ltd | Health & social care | 2020 |
| A T Brickwork (London) Limited | Construction | 2023 |
| A T Dental Excellence Ltd | Health & social care | 2016 |
| A T Electric Ltd | Construction | 2020 |
| A T Muyiwa Limited | Construction | 2018 |
| A T Plumbing Solutions Ltd | Construction | 2024 |
| A T S a I Limited | Professional & scientific | 2020 |
| A T S Services Limited | Professional & scientific | 1997 |
| A T Store Ltd | Wholesale & retail | 2025 |
| A T Suny Service Ltd | Administrative & support | 2017 |
| A T Traders Limited | Wholesale & retail | 2017 |
| A T Used Cars Ltd | Wholesale & retail | 2026 |
| A T.I.M.E. Limited | Administrative & support | 2008 |
| A Tale of Colours Ltd | Wholesale & retail | 2022 |
| A Tangible Future Ltd | Wholesale & retail | 2024 |
| A Tasca Peterborough Ltd | Hospitality | 2017 |
| A Taste of Africa Ltd | Other services | 2019 |
| A Taste of Kiki’S Kitchen Ltd | Manufacturing | 2024 |
| A Taste of OUR Muse Limited | Wholesale & retail | 2023 |
| A Taste of Paphos Limited | Hospitality | 2025 |
| A Taste of Space Partners Limited | Extraterritorial | 2017 |
| A Taste of Spain Ltd | Wholesale & retail | 2019 |
| A Taste of Texas Fest Limited | Administrative & support | 2026 |
| A Taste of the Edge Ltd | Hospitality | 2023 |
| A Taste of West Ltd | Hospitality | 2025 |
| A Taverna DO Barros Ltd | Hospitality | 2021 |
| A Tavola Consulting Ltd | Professional & scientific | 2023 |
| A Tavola Limited | Professional & scientific | 2009 |
| A Team Advisory Limited | Professional & scientific | 2026 |
| A Team Auto (ATA) Ltd | Wholesale & retail | 2024 |
| A Team Finance Limited | Professional & scientific | 2011 |
| A Team Occasion Ltd | Administrative & support | 2015 |
| A Team Projected Limited | Professional & scientific | 2016 |
| A Team Real Estate Ltd | Real estate | 2025 |
| A Team Talent Ltd | Other services | 2019 |
| A Team United Ltd | Real estate | 2024 |
| A Teens. Thing Ltd | Information & communication | 2019 |
| A TEN Year Noose Limited | Other services | 1999 |
| A Tentative Atelier UK Limited | Wholesale & retail | 2023 |
| A That's IT Company Ltd | Hospitality | 2022 |
| A Thermal Ltd | Construction | 2024 |
| A Think Labs Ltd | Professional & scientific | 2019 |
| A Thousand Acres Ltd | Wholesale & retail | 2021 |
| A Thousand Decisions Ltd | Professional & scientific | 2022 |
| A Thousand Hills Ltd | Financial services | 2013 |
| A Thousand Lives Ltd | Arts & recreation | 2025 |
| A Throw of Dice Touring Limited | Arts & recreation | 2006 |
| A Time to Heal Ltd | Health & social care | 2021 |
| A to B Painting & Decorating Ltd | Construction | 2025 |
| A to B Property Refurbish Limited | Construction | 2015 |
| A to B Van Removals Ltd | Transport & logistics | 2024 |
| A to There Solutions Ltd | Professional & scientific | 2016 |
| A to Z 4U Ltd | Information & communication | 2007 |
| A to Z 4YOU Ltd | Wholesale & retail | 2018 |
| A to Z Academy International Ltd | Professional & scientific | 2024 |
| A to Z Accountancy Services Limited | Professional & scientific | 2023 |
| A to Z Affordable Construction Ltd | Construction | 2024 |
| A to Z Barber Ltd | Other services | 2018 |
| A to Z Block Management Limited | Real estate | 2018 |
| A to Z Brothers Limited | Financial services | 2019 |
| A to Z Building Construction Ltd | Construction | 2023 |
| A to Z Building Maintenance and Services Ltd | Construction | 2020 |
| A to Z Business Consultants Limited | Professional & scientific | 2026 |
| A to Z Catering (2008) Limited | Financial services | 2008 |
| A to Z Catering LLP | | 2008 |
| A to Z Catering Supplies Limited | Wholesale & retail | 1998 |
| A to Z Cleaning Master Ltd | Construction | 2021 |
| A to Z Communications and Strategy Ltd | Professional & scientific | 2020 |
| A to Z Components Limited | Wholesale & retail | 2017 |
| A to Z Consult Limited | Administrative & support | 2012 |
| A to Z Consultants Limited | | 1987 |
| A to Z DBS Ltd | Construction | 2025 |
| A to Z Delivery Ltd | Transport & logistics | 2018 |
| A to Z Design and Glass Ltd | Construction | 2019 |
| A to Z Designer Ltd | Manufacturing | 2015 |
| A to Z Developer Ltd | Construction | 2022 |
| A to Z DRY Cleaner & Launderette Ltd | Other services | 2023 |
| A to Z Education Ltd | Professional & scientific | 2019 |
| A to Z Express Ltd | Wholesale & retail | 2022 |
| A to Z Extra Business Solution Ltd | Health & social care | 2016 |
| A to Z Furnishings Ltd | Manufacturing | 2021 |
| A to Z Halal Meat Limited | Wholesale & retail | 2024 |