| Aston Consulting Group Ltd | Professional & scientific | 2023 |
| Aston Electrical Limited | Construction | 1997 |
| Astra Express Ltd | Transport & logistics | 2015 |
| Astraflow AI Solutions Ltd | Wholesale & retail | 2025 |
| Astrionic Systems Ltd | Information & communication | 2018 |
| AT Home Healthcare Ltd | Health & social care | 2021 |
| AT Last Consulting Limited | Professional & scientific | 2025 |
| AT Reid Consulting Limited | Professional & scientific | 2021 |
| ATC - Alloush Trading & Contracting Ltd | Professional & scientific | 2019 |
| Aters Group Ltd | Real estate | 2025 |
| Atha Ltd | Construction | 2025 |
| Athens Consulting Limited | Financial services | 2016 |
| Atik Flooring Solutions Ltd | Wholesale & retail | 2019 |
| Atille Security Limited | Administrative & support | 2025 |
| Atkins Prestwood Limited | Construction | 1967 |
| Atlantic Publishing & Packaging Services Limited | Information & communication | 2002 |
| Atlas Property Advisors Ltd | Real estate | 2009 |
| ATO Studio Ltd | Other services | 2021 |
| Atom Lighting Limited | Information & communication | 2021 |
| ATP Lane Limited | Real estate | 2020 |
| Auctus Solutions Limited | Administrative & support | 2017 |
| Audiofy Limited | Information & communication | 2025 |
| Audley Holdings Limited | Professional & scientific | 1997 |
| August Research International Ltd | Professional & scientific | 2022 |
| Augustoceancoral Investments Limited | Financial services | 2009 |
| Aurialis Ltd. | Wholesale & retail | 2011 |
| Aurumrosa Limited | Professional & scientific | 2025 |
| Authentic Greek Ltd | Hospitality | 2022 |
| Auto Coding & Adas Ltd | Wholesale & retail | 2026 |
| Autogrid Limited | Other services | 2025 |
| Autokitchen UK Limited | Information & communication | 2014 |
| Automation Instrumentation Engineering Ltd | Professional & scientific | 2022 |
| Autometrix Ltd | Information & communication | 2023 |
| AV Surveyors Ltd | Professional & scientific | 2026 |
| Avenue Ealing Limited | Construction | 2013 |
| Avis & West Builders Ltd | Real estate | 2024 |
| Avis Properties Ltd | Real estate | 2021 |
| Avocation Assets Ltd | Real estate | 2024 |
| Aweinspiring Properties Limited | Real estate | 2021 |
| AWR Projects Ltd | Professional & scientific | 2025 |
| AXE Property Management Limited | Real estate | 2024 |
| Axia Accountants Limited | Professional & scientific | 2022 |
| Axial Legal Limited | Administrative & support | 2020 |
| Axiom Engineering Services Ltd | Professional & scientific | 2019 |
| Ayguns Fish and Chips Limited | Hospitality | 2026 |
| AZ Builds Ltd | Real estate | 2024 |
| AZ Teas UK Ltd | Wholesale & retail | 2023 |
| Aztlan Limited | Administrative & support | 2010 |
| Azuki Accounts Limited | Professional & scientific | 2016 |
| Azul Enterprises Limited | Professional & scientific | 2018 |
| B and L Property Group Ltd | Real estate | 2016 |
| B-A-R Electrical and Mechanical Services Limited | Construction | 2014 |
| B-A-R Services Group Limited | Administrative & support | 2020 |
| B.Whitewood(Northwood)Limited | Administrative & support | 1964 |
| B2G Property Group Ltd | Real estate | 2021 |
| Babaluma Music Limited | Manufacturing | 2022 |
| Bacel UK Ltd | Professional & scientific | 2021 |
| Bacw Consulting Limited | Other services | 2021 |
| Bahra Lettings Limited | Real estate | 2018 |
| Baikel Trading Limited | Construction | 2020 |
| Bailie Harkness Tennis Limited | Arts & recreation | 2007 |
| Bailiefin Properties Limited | Construction | 2020 |
| Baker Bond & Green Limited | Education | 2014 |
| Baker Investments Limited | Real estate | 2019 |
| Balance the Board Ltd | Professional & scientific | 2022 |
| Ballard Property Group Limited | Financial services | 2025 |
| Ballards Commissioning Ltd | Professional & scientific | 2010 |
| Ballav Medical Services Limited | Health & social care | 2021 |
| Bamford Properties Ltd | Real estate | 2019 |
| Bani Traders Ltd | Wholesale & retail | 2024 |
| Barkhill Capital Limited | Financial services | 2025 |
| Barley Mews Limited | Real estate | 2017 |
| Barralet Investments Limited | Other services | 1988 |
| Barrwell Property Limited | Real estate | 2020 |
| Barry Mccarthy Building & Roofing Limited | Construction | 2005 |
| Bart Toorenaar Advisory Limited | Professional & scientific | 2021 |
| Basani Properties Ltd | Real estate | 2018 |
| Base Recruitment UK Limited | Administrative & support | 2009 |
| Basus Private Limited | Health & social care | 2022 |
| Batchelder Ltd | Administrative & support | 2024 |
| Batchworth Capital Ltd | Real estate | 2026 |
| Batchworth Estates Ltd | Administrative & support | 2014 |
| Batchworth Properties Limited | Real estate | 1995 |
| Bathwick Corporation Limited | Professional & scientific | 1996 |
| Bathwick Properties Limited | Real estate | 1998 |
| Baygold Developments Ltd | Real estate | 2006 |
| Baysium Ltd | Professional & scientific | 2022 |
| Bbpr Ltd | Professional & scientific | 2020 |
| Bcafitness Limited | Arts & recreation | 2023 |
| BCP3 Limited | Professional & scientific | 2024 |
| BD Precision Engineers Limited | Manufacturing | 2014 |
| Bdkd Properties Ltd | Real estate | 2025 |
| BE My Tutor EA Ltd | Education | 2023 |
| BE My Tutor Ltd | Education | 2021 |
| Beaconway Consulting Limited | Professional & scientific | 2014 |
| Bearded Braai Ltd | Manufacturing | 2021 |
| Bearpark Homes Ltd | Construction | 2005 |
| Bedrock Capital Ltd | Financial services | 2021 |
| Beechcroft Builders Limited | Construction | 2007 |
| BEL Shine Janitorial Limited | Administrative & support | 2025 |