| Airpocket Designs Limited | Professional & scientific | 1995 |
| Airport Capacity Solutions Limited | Professional & scientific | 2007 |
| Airports Direct (MK) Limited | Administrative & support | 2004 |
| Airtech Refrigeration Limited | Professional & scientific | 2021 |
| Airtech Vehicle Air Conditioning and Heating Ltd | Energy | 2024 |
| Aisosa Osasogie Global Ventures Ltd | Hospitality | 2024 |
| AIT Home Delivery UK Ltd. | Administrative & support | 2009 |
| AIT Logistics Ltd | Extraterritorial | 2020 |
| Aitken Electrical Contractors Ltd | Construction | 2014 |
| Aitken Homes Limited | Real estate | 2020 |
| Aitm Ltd | Information & communication | 2014 |
| Aitma Limited | Financial services | 2018 |
| Aixcoin Ltd | Information & communication | 2026 |
| Aixin Upward Technology Co., Ltd | Wholesale & retail | 2021 |
| AJ Affiliates Ltd | Professional & scientific | 2024 |
| AJ Bees Ltd | Real estate | 2023 |
| AJ Cycle Hire Ltd | Administrative & support | 2020 |
| AJ Cycles Limited | Wholesale & retail | 2016 |
| AJ Employment Ltd | Information & communication | 2013 |
| AJ Partners & Trading Ltd | Hospitality | 2024 |
| AJ Property Expert Ltd | Real estate | 2025 |
| AJ Pure Clean Ltd | Administrative & support | 2024 |
| AJ Security and Cabling Solutions Limited | Construction | 2021 |
| Aj's 1968 Limited | Extraterritorial | 2014 |
| AJ100 Limited | Professional & scientific | 2015 |
| AJB Commercial Services Limited | Administrative & support | 2010 |
| AJB Tech Solutions Ltd | Information & communication | 2021 |
| AJD Estate Planning Limited | Professional & scientific | 2020 |
| AJI Builders Limited | Construction | 2026 |
| AJI Tech Ltd | Information & communication | 2026 |
| Ajil Ltd | Health & social care | 2021 |
| Ajis Ventures Ltd | Transport & logistics | 2019 |
| Ajjwa Group Ltd | Real estate | 2025 |
| Ajjwa Ltd | Real estate | 2020 |
| AJL Sports and Exercise Medicine Ltd | Health & social care | 2022 |
| AJM Property Associates Ltd | Real estate | 2020 |
| AJM Supply Chain Consulting Ltd | Transport & logistics | 2019 |
| AJM Transport (UK) PTY Limited | Transport & logistics | 2019 |
| Ajmw Limited | Professional & scientific | 2017 |
| AJP Carpentry Limited | Manufacturing | 2023 |
| AJR Driving Ltd | Transport & logistics | 2025 |
| AJR Quality Ltd | Professional & scientific | 2026 |
| Ajrmderm Ltd | Health & social care | 2024 |
| AJS Express Parcels Limited | Transport & logistics | 2018 |
| AJS Private Ltd | Wholesale & retail | 2026 |
| AJS Technical Services (UK) Limited | Professional & scientific | 2013 |
| AJS Trailer Servicing Ltd | Wholesale & retail | 2021 |
| Ajv&V Property Investment Ltd | Real estate | 2024 |
| AJW Automotive Limited | Professional & scientific | 2023 |
| AJW Investment Group Ltd | Wholesale & retail | 2017 |
| AJW Plant & Vehicle Services Limited | Wholesale & retail | 2013 |
| Ajwa Healthcare Ltd | Health & social care | 2024 |
| AK Abashe Limited | Health & social care | 2025 |
| AK Building and Roofing Services Limited | Construction | 2022 |
| AK Dental Care Limited | Health & social care | 2021 |
| AK Event Productions Ltd | Administrative & support | 2026 |
| AK Fire Safety Ltd | Public administration | 2023 |
| AK Green Energy Ltd | Construction | 2024 |
| AK Groundworks and Paving Ltd | Construction | 2024 |
| AK Infosystems Ltd | Information & communication | 2024 |
| AK RK Traders Ltd | Hospitality | 2022 |
| AK Trenchless Limited | Construction | 1999 |
| Ak-Mac Services Ltd | Manufacturing | 2024 |
| Ak-Tivities Ltd | Education | 2018 |
| AKA Therapy Ltd | Wholesale & retail | 2019 |
| Akari Electrical Ltd | Construction | 2025 |
| Akasaka NN Ltd | Hospitality | 2016 |
| Akash Tandoori Restaurant (Wellingborough) Limited | Hospitality | 1991 |
| Akashic Tree Ltd | Administrative & support | 2025 |
| Akaz Limited | Other services | 2025 |
| Akber Foods Ltd | Hospitality | 2026 |
| Akbor ALI Investments Limited | Real estate | 2022 |
| Akbor ALI Solutions Limited | Administrative & support | 2023 |
| Akcent Aspect Ltd | Construction | 2022 |
| Akeba Limited | Extraterritorial | 2007 |
| Akerlof (Holdings) Limited | Financial services | 2022 |
| Akerlof Limited | Professional & scientific | 2019 |
| AKG Design & Build Ltd | Professional & scientific | 2024 |
| AKG Trading (UK) Limited | Manufacturing | 2009 |
| Akis Solar (UK) Ltd | Other services | 2023 |
| Akiynam Limited | Wholesale & retail | 2023 |
| Akoso Refuge Limited | Real estate | 2026 |
| Akou Ltd | Information & communication | 2019 |
| AKS Logistics Ltd | Transport & logistics | 2022 |
| AKS Training Ltd | Professional & scientific | 2017 |
| AKW Studio Limited | Information & communication | 2023 |
| Akwapoks Care Solutions Ltd | Health & social care | 2023 |
| AKX Logistics Ltd | Transport & logistics | 2025 |
| Akyani Limited | Real estate | 2026 |
| Akyeman Ltd | Health & social care | 2023 |
| AL Baraqat Ltd | Administrative & support | 2021 |
| AL Bayt Limited | Real estate | 2020 |
| AL Burak Travels Ltd | Administrative & support | 2025 |
| AL Consultancy Ltd | Information & communication | 2011 |
| AL Dance Academy Ltd | Education | 2026 |
| AL Digit AL Limited | Professional & scientific | 2025 |
| AL Education Ltd | Education | 2015 |
| AL Falah London Ltd | Wholesale & retail | 2024 |
| AL Falah Northants Ltd | Other services | 2016 |
| AL Fattah Books Ltd | Wholesale & retail | 2025 |