| AAT Wind Energy Limited | Ayr | 2009 |
| Aata Ltd | Kingston Upon Thames | 2019 |
| Aatax Limited | Walsall | 2007 |
| Aataxco Ltd | Birmingham | 2020 |
| Aate Limited | Watford | 2016 |
| Aathomas Limited | London | 2019 |
| Aatif Hashmi Consultancy Ltd | Gateshead | 2019 |
| Aatos Legal Technology Ltd | Warwick | 2023 |
| Aatw Limited | London | 2007 |
| AAU Accounting Ltd | Birmingham | 2020 |
| AAU Designs Limited | London | 1998 |
| AAU Investments Limited | London | 2022 |
| Aaunel Limited | Ashford | 2017 |
| Aaurelia Consulting Ltd | London | 2019 |
| Aaurus Limited | Isleworth | 2024 |
| Aaustin Engineering Limited | Yarm | 2017 |
| AAV Architecture Ltd | Strensham | 2022 |
| AAV Research Limited | Budleigh Salterton | 2024 |
| Aava Ltd | Burnham-On-Crouch | 2006 |
| Aavaa Group Ltd | Moira | 2022 |
| Aavagard Law UK Limited | King'S Lynn | 2025 |
| Aavantgarde BIO UK Limited | London | 2023 |
| Aavi Ltd | Bushey | 2012 |
| Aavi Management Limited | Harrow | 2018 |
| Aavior Ltd | London | 2025 |
| Aavrus & Co Ltd | Ilford | 2011 |
| Aavsci Limited | Ilford | 2019 |
| AAW Law Limited | London | 2019 |
| Aawan Business Partnering Limited | Harrow | 2011 |
| Aawatson Project Consulting Limited | York | 2011 |
| Aawaz Communications Limited | London | 2001 |
| Aaworks Ltd | London | 2026 |
| AAX Accountants Ltd | Portishead | 2015 |
| Aaxal Limited | Bedford | 2007 |
| AAY Associates Limited | Chesham | 2019 |
| AAY Consultancy Limited | London | 2017 |
| Aayan & Co Limited | Ilford | 2014 |
| Aayasir Limited | Preston | 2023 |
| Aayg Ltd | Waterlooville | 2011 |
| Aays Technologies UK Limited | Rickmansworth | 2020 |
| Aayubo Limited | Aylesbury | 2025 |
| AAZ Engineering Services Ltd | London | 2025 |
| AAZ Solutions Limited | London | 2025 |
| AB & AR Holdings Limited | Folkestone | 2012 |
| AB & Co Accountancy Ltd | London | 2026 |
| AB & Co Accountants Ltd | Warrington | 2020 |
| AB & Co Accounting &Tax Services Limited | Maidstone | 2016 |
| AB & Tax Services Ltd | Watlington | 2013 |
| AB 2014 Limited | Reading | 2014 |
| AB 3RD Sector Limited | Thornhill | 2020 |
| AB Accountancy Care Ltd | Waltham Abbey | 2025 |
| AB Accountancy Ltd | Ely | 2020 |
| AB Accountancy Solutions Ltd | Workington | 2018 |
| AB Accountancy South West Ltd | Holsworthy | 2023 |
| AB Accountants Ltd | London | 2019 |
| AB Accounting & Tax Consultants Ltd | London | 2019 |
| AB Accounting and Taxation Services Limited | Birmingham | 2011 |
| AB Accounting Ltd | Stanmore | 2009 |
| AB Accounting Services Ltd | Bedford | 2004 |
| AB Accounts Limited | Slough | 2023 |
| AB Advisors Limited | London | 2005 |
| AB Advisory Group Ltd | London | 2025 |
| AB Aero Consultancy Ltd | Mansfield | 2026 |
| AB Aerospace Consulting Limited | Clevedon | 2022 |
| AB Aesthetic Services Limited | Lymm | 2020 |
| AB Agile Ltd | Hove | 2025 |
| AB Aircon Solutions Ltd | Warrington | 2022 |
| AB and P Developments Limited | Hounslow | 2016 |
| AB Architecture (Kent) Ltd | Kent | 2023 |
| AB Architecture Limited | Winsford | 2013 |
| AB Audio Visual Ltd | Wisbech | 2002 |
| AB Beauty Consultancy Limited | Leighton Buzzard | 2019 |
| AB Blue Compass Ltd | London | 2025 |
| AB Bookkeeping & Accountancy Ltd | Westerham | 2016 |
| AB Books Ltd | London | 2024 |
| AB Building Design Limited | Stockton-On-Tees | 2007 |
| AB Business Advisory Ltd | London | 2026 |
| AB Business Assistance Limited | London | 2023 |
| AB Business Change and Transformation Ltd | Nottingham | 2024 |
| AB Business Coaching Limited | Huntingdon | 2004 |
| AB Business Consultancy Limited | London | 2015 |
| AB Business Consulting Ltd | Brentford | 2015 |
| AB C&E Ltd | London | 2021 |
| AB Capital Ltd | London | 2018 |
| AB Care Consultancy Ltd | Harlow | 2024 |
| AB Change Management Ltd | Rushden | 2024 |
| AB Coaching and Consulting Limited | Dalkeith | 2020 |
| AB Coaching and Leadership Limited | Devizes | 2007 |
| AB Coaching Limited | Camberley | 2021 |
| AB Collective Ltd | London | 2025 |
| AB Commercial Management Ltd | Ferndown | 2017 |
| AB Commercial Services (UK) Limited | London | 2020 |
| AB Comms Limited | London | 2020 |
| AB Communications & Marketing Ltd | London | 2025 |
| AB Communications PR Limited | Camberley | 2009 |
| AB Construction Consultancy Ltd | London | 2021 |
| AB Construction Management Consultants Ltd | Glasgow | 2020 |
| AB Consulere Limited | London | 2019 |
| AB Consult International Ltd | Aberdeen | 2025 |
| AB Consult UK Ltd | London | 2019 |