| Ace Recovery 24 Ltd | Wholesale & retail | 2025 |
| Ace Repairs London Ltd | Wholesale & retail | 2024 |
| Acee Investments Limited | Real estate | 2026 |
| Aces Consultancy Ltd | Professional & scientific | 2025 |
| ACH Digital Ltd | Information & communication | 2019 |
| Achilles Clean Limited | Administrative & support | 2022 |
| Ackroyd Investments Ltd | Real estate | 2025 |
| Acom Fish Ltd | Hospitality | 2020 |
| Acorn Vehicle Logistics Limited | Other services | 2008 |
| Acqua Holding Limited | Financial services | 2022 |
| Acqua Investments Limited | Real estate | 2022 |
| Acre Barnet Limited | Real estate | 2021 |
| Actinium Media Ltd | Information & communication | 2012 |
| Action Research Holdings Ltd | Professional & scientific | 2026 |
| Action Research Network (ARN) Limited | Professional & scientific | 2022 |
| Active Trading Ltd | Manufacturing | 2019 |
| Actu Property Group Limited | Administrative & support | 2021 |
| Actworth Limited | Real estate | 1970 |
| AD Company Holding UK Ltd | Financial services | 2025 |
| AD Performing Arts Ltd | Arts & recreation | 2021 |
| AD Property Management and Lettings Ltd | Real estate | 2017 |
| AD Worktops Ltd | Manufacturing | 2025 |
| ADA Borehamwood Cafe Limited | Hospitality | 2023 |
| ADA Business Ltd | Professional & scientific | 2023 |
| ADA Consultants UK Ltd | Professional & scientific | 2024 |
| Adakas Ltd | Information & communication | 2021 |
| Adalgo Limited | Administrative & support | 2008 |
| Adam and Co Properties Ltd | Real estate | 2025 |
| Adam and EVE Organisation Limited | Financial services | 2025 |
| Adam and SU Property Ltd | Real estate | 2026 |
| Adam Kawalek Ltd | Transport & logistics | 2019 |
| Adamanna Limited | Information & communication | 2016 |
| Adams Family Services Ltd | Wholesale & retail | 2025 |
| Adan Distribution Ltd | Wholesale & retail | 2025 |
| Adaptive Risk Technology Limited | Information & communication | 2002 |
| Adastra Global Investments Limited | Administrative & support | 2008 |
| Adatwa Marketing Ltd | Other services | 2013 |
| Adck Ltd | Construction | 2025 |
| Addae Construction Limited | Construction | 2022 |
| Addc Properties Ltd | Real estate | 2026 |
| Addismiller Limited | Other services | 2019 |
| ADE2 Limited | Financial services | 2024 |
| Adejuwon Complete Care Solutions Limited | Health & social care | 2019 |
| Adekzpharm Limited | Health & social care | 2024 |
| Adenai Ltd | Manufacturing | 2024 |
| Adept Consultancy Services Ltd | Wholesale & retail | 2022 |
| Adept Scaffolding Ltd | Construction | 2022 |
| Ades Pharm Ltd | Health & social care | 2018 |
| Adesso Solutions Limited | Wholesale & retail | 2021 |
| Adet Facilities Ltd | Administrative & support | 2025 |
| Adex Solar Social Enterprise UK Limited | Other services | 2017 |
| Adfs Chauffeur Services Limited | Transport & logistics | 2015 |
| Adgp Properties Ltd | Real estate | 2019 |
| ADI. P Electrical Ltd | Construction | 2021 |
| Aditya & Co Limited | Wholesale & retail | 2020 |
| Adlc Construction Ltd | Construction | 2015 |
| Adlertech Ltd | Wholesale & retail | 2018 |
| ADM Food & Wine Ltd | Wholesale & retail | 2011 |
| ADM Interiors Limited | Construction | 2008 |
| ADM London Investments Limited | Construction | 2023 |
| ADM Tiling Limited | Construction | 2017 |
| ADM Transfer Limited | Transport & logistics | 2026 |
| Admin Tools Ltd | Wholesale & retail | 2024 |
| ADN Pro Limited | Financial services | 2016 |
| ADO VEG Ltd | Wholesale & retail | 2020 |
| Adobe Real Estate Ltd | Real estate | 2019 |
| Adobix Ltd | Administrative & support | 2023 |
| Adomah Healthcare Limited | Health & social care | 2015 |
| Adomoo Ltd | Health & social care | 2018 |
| Adoni Infotech Ltd | Information & communication | 2020 |
| Adonis Refuge Community C.I.C. | Information & communication | 2023 |
| Adorn Designs Ltd | Wholesale & retail | 2025 |
| ADP London Studios Ltd | Construction | 2025 |
| ADS Live Studios Ltd | Information & communication | 2025 |
| Adstylist Limited | Professional & scientific | 2020 |
| ADT Building Limited | Construction | 2018 |
| ADV Stays Ltd | Real estate | 2023 |
| Advance Tyres Holdings Limited | Wholesale & retail | 1984 |
| Advanced Eco Blast Limited | Construction | 2014 |
| Advanced Electrical Engineering Solutions Ltd | Manufacturing | 2022 |
| Advanced Vision Surveillance Limited | Other services | 2001 |
| Advantage Secretarial Limited | Administrative & support | 2009 |
| Advent Consult Ltd | Information & communication | 2018 |
| Adventure Homes Ltd | Real estate | 2017 |
| Adventure PUB Co Ltd | Hospitality | 2018 |
| Adzelo Ltd | Wholesale & retail | 2025 |
| AE Plumbing & Drainage LDN Limited | Construction | 2024 |
| AE Signature Aesthetics Ltd | Health & social care | 2025 |
| Aegean Electric Ltd | Construction | 2025 |
| AEK Construction Ltd | Construction | 2019 |
| AEK Health Ltd | Professional & scientific | 2025 |
| Aemaa Limited | Other services | 2025 |
| Aenaon Limited | Professional & scientific | 2017 |
| Aeroscape Experiences Limited | Administrative & support | 2024 |
| Aerotech Realm Ltd | Wholesale & retail | 2018 |
| Aerotek Engineering and IT Solutions Ltd | Information & communication | 2022 |
| AES Drainage Ltd | Water & waste | 2025 |
| AES Smart Metering Ltd | Construction | 2013 |
| Aesthetic Stone Ltd | Construction | 2017 |
| Aesthetics by Marika Ltd | Other services | 2022 |