| Agricultural Building Construction Ltd | Construction | 2016 |
| Agriserve Limited | Agriculture & fishing | 1984 |
| Agritexuk Ltd | Agriculture & fishing | 2026 |
| Ahtera Ltd | Wholesale & retail | 2018 |
| AHW (Operating) Co Limited | Professional & scientific | 2012 |
| AHW (Property) Co Limited | Real estate | 2013 |
| Aibes Care Ltd | Health & social care | 2018 |
| Aibes Care Training Solutions Ltd | Administrative & support | 2023 |
| Aidens Roofing and Property Management Ltd | Construction | 2026 |
| Aimee's Hair Limited | Other services | 2025 |
| AIONIX11 Limited | Information & communication | 2025 |
| Airbrushed Aesthetics Ltd | Other services | 2019 |
| Airfield Shoot Ltd | Arts & recreation | 2021 |
| Aivatrans Limited | Transport & logistics | 2008 |
| AJ Arch Limited | Arts & recreation | 2022 |
| AJ Logistic Solutions Ltd | Transport & logistics | 2025 |
| AJ Property & Letting Ltd | Real estate | 2026 |
| AJ Select Properties UK Ltd | Real estate | 2026 |
| AJ Team Installation (2013) Limited | Construction | 2016 |
| AJA Trans Ltd | Administrative & support | 2018 |
| AJB Group (Carpentry) Ltd | Manufacturing | 2021 |
| AJC Trans Ltd | Transport & logistics | 2024 |
| AJD Global Services Limited | Professional & scientific | 2018 |
| AJF Groundworks Limited | Construction | 2022 |
| AJF Home Improvements Ltd | Construction | 2024 |
| AJG and SJG Ltd | Real estate | 2026 |
| AJH Layers Ltd | Agriculture & fishing | 2022 |
| AJO Designs Limited | Manufacturing | 2017 |
| AJP Mobile Technician Ltd | Wholesale & retail | 2025 |
| AJS Asset Care Limited | Professional & scientific | 2020 |
| AJS Control & Automation Limited | Construction | 2008 |
| AJS Design LAB Ltd | Manufacturing | 2018 |
| AJS Holdings (Spalding) Limited | Financial services | 2022 |
| AJS Service & Support Limited | Construction | 2021 |
| AJW Commerce Ltd | Wholesale & retail | 2024 |
| AK Expres Ltd | Transport & logistics | 2021 |
| AK Garden Services Ltd. | Construction | 1998 |
| AK Transport 1991 Ltd | Transport & logistics | 2018 |
| Akaje Management 2025 Limited | Information & communication | 2025 |
| Akat 969 Ltd | Wholesale & retail | 2018 |
| AKD Care Limited | Administrative & support | 2015 |
| AKL Interim Services Ltd | Professional & scientific | 2019 |
| Aktc Limited | Professional & scientific | 2020 |
| Aktobe Holdings Ltd | Mining & quarrying | 2022 |
| AL Wazed Property Holdings Ltd | Real estate | 2026 |
| Alan J Wilkinson Limited | Real estate | 1968 |
| ALB Technical Solutions Ltd | Information & communication | 2026 |
| Albert James Estate Agents Ltd | Real estate | 2023 |
| Albert James Limited | Real estate | 2014 |
| Albert M C Limited | Wholesale & retail | 2008 |
| Alchemia Ltd | Professional & scientific | 2025 |
| Alecu Marian Universal Transport Ltd | Transport & logistics | 2015 |
| Alekmove Ltd | Transport & logistics | 2026 |
| Alert Medical Services Ltd | Health & social care | 2021 |
| Aleser Trans Ltd | Transport & logistics | 2017 |
| Alex Aldrich PR Ltd | Professional & scientific | 2022 |
| Alexdei Trans Ltd | Transport & logistics | 2014 |
| Alexeric Ltd | Transport & logistics | 2015 |
| Alexiown Ltd | Professional & scientific | 2018 |
| Alexmondo Ltd | Transport & logistics | 2024 |
| Alexsimo Ltd | Transport & logistics | 2018 |
| Alexthetrader Ltd | Information & communication | 2025 |
| Alfie Consulting Lead Generation Limited | Professional & scientific | 2017 |
| Algiukas Veza Ltd | Transport & logistics | 2017 |
| Alice Liveing Limited | Administrative & support | 2015 |
| Aliflo Trans Ltd | Transport & logistics | 2017 |
| Alina Trans Ltd | Administrative & support | 2016 |
| Alix C Consultancy Ltd | Professional & scientific | 2015 |
| ALL About ALF & ADA Ltd | Arts & recreation | 2023 |
| ALL About Ashley Limited | Arts & recreation | 2018 |
| ALL Aspects Agency Limited | Health & social care | 2019 |
| ALL Aspects Car Care 2020 Ltd | Wholesale & retail | 2020 |
| ALL Aspects Construction (Midlands) Ltd | Construction | 2020 |
| ALL Bridges Limited | Health & social care | 2009 |
| ALL Eight Group Ltd | Extraterritorial | 2024 |
| ALL Eight Ltd | Extraterritorial | 2024 |
| ALL Port Solutions Ltd | Transport & logistics | 2025 |
| ALL Utility Limited | Water & waste | 2020 |
| ALL Utility Services Ltd | Water & waste | 2024 |
| ALL Ways Green Limited | Construction | 2007 |
| Allen Financial Services Ltd | Financial services | 2015 |
| Allexy Ltd | Transport & logistics | 2025 |
| Allied Builders UK Limited | Construction | 2007 |
| Allied Commercial Cleaning Limited | Administrative & support | 2014 |
| Allied Developments (Northampton) Ltd | Construction | 2023 |
| Allied Health South Lincolnshire Ltd | Health & social care | 2016 |
| Allied Parks Group Ltd | Real estate | 2018 |
| ALM Breedon Properties Limited | Households | 2022 |
| Almond Walker LLP | | 2025 |
| Aloys Junior Enterprise Ltd | Arts & recreation | 2024 |
| ALP Engineering Solutions Ltd | Professional & scientific | 2026 |
| Alpha 7 Trans Ltd | Transport & logistics | 2025 |
| Alpha Beta Live Limited | Professional & scientific | 2009 |
| Alpha Control Specialists Ltd | Construction | 2014 |
| Alpha Logistics Ltd | Professional & scientific | 2016 |
| Alpha Plants Ltd | Agriculture & fishing | 2020 |
| Alpha Solar Specialists Ltd | Construction | 2025 |
| Alpha Traffic Management Ltd | Construction | 2026 |
| Alps Carpentry & Bespoke Joinery Ltd | Construction | 2026 |
| Alss Accounting & Consulting Ltd | Professional & scientific | 2021 |