| Advanced Solutions Group Limited | Kenilworth | 2015 |
| Advanced Spares Limited | Worthing | 2022 |
| Advanced Stock Solutions Ltd | Smethwick | 2017 |
| Advanced Systems House Limited | Richmond | 2009 |
| Advanced Technology Tackle Limited | Aldershot | 2016 |
| Advanced TEK Co., Ltd | London | 2009 |
| Advanced Trading & Infrastructure Solutions Limited | Esher | 2024 |
| Advanced Vetcare Ltd | Bristol | 2007 |
| Advanceflow Limited | Beckenham | 2024 |
| Advancetrack Limited | | 2006 |
| Advancetrack Outsourcing Limited | | 2006 |
| Advancive Ltd | Woodstock | 2007 |
| Advantage Asset Finance Ltd | Solihull | 2008 |
| Advantage Awards Limited | Pershore | 2012 |
| Advantage Blow Mouldings Limited | Presteigne | 2022 |
| Advantage Coaching Limited | London | 2021 |
| Advantage Direct Finance Limited | Solihull | 2009 |
| Advantage Global Trade Exports Limited | Warwick | 2012 |
| Advantage Insight Limited | Newport Pagnell | 2014 |
| Advantage Maintenance Limited | Woking | 1991 |
| Advantage Motor Finance Limited | Solihull | 1999 |
| Advantage Partner Finance Ltd | Solihull | 2009 |
| Advantage Presteigne Limited | Presteigne | 2023 |
| Advantage Pumping Solutions Limited | Hull | 2014 |
| Advantage Sports Maintenance Limited | Woking | 1991 |
| Advantage Windscreen Wash Systems Limited | Presteigne | 2022 |
| Advantage Woman Limited | Dunstable | 2013 |
| ADVANTAGE4U Ltd | Solihull | 2008 |
| Advantex Ltd | Bury | 2019 |
| Advantica Solutions Ltd | Edinburgh | 2018 |
| Advantis Science Enterprise Co., Ltd. | London | 2008 |
| Advecto Limited | Telford | 2011 |
| Advencas Ltd | Sandy | 2024 |
| Advent Mechanical Services Ltd | East Horsley | 1986 |
| Adventa Limited | Hampshire | 1994 |
| Adventure Golf Construction Limited | Bexhill On Sea | 2014 |
| Adventure Golf Developments Ltd | Eastbourne | 2019 |
| Adventure in Business Ltd | Newport | 2015 |
| Adventure Marine Yachting Ltd | Blackpool | 2024 |
| Adventure Nomad Ltd | Trowbridge | 2024 |
| Adventure Nutrition Limited | London | 2024 |
| Adventure of the Seas Ltd | London | 2020 |
| Adventure Pawtraits Ltd | Newcastle-Under-Lyme | 2020 |
| Adventure Sport Events Limited | London | 2000 |
| Adventure Types Ltd | Seaton | 2019 |
| Adventurer Management Ltd | Coventry | 2013 |
| Adventures and Tours Limited | Blackpool | 2022 |
| Adventures by Elle Ltd | Stourport-On-Severn | 2022 |
| Adverb MIX Ltd | London | 2025 |
| Advert Holdings Ltd | Norwich | 2021 |
| Adverticals (UK) Limited | Kingston Upon Hull | 2013 |
| Advertiser North London Group (Holdings) Limited | London | 1983 |
| Advertiser North London Limited | London | 1972 |
| Advertiser UK Limited | Birmingham | 2021 |
| Advertising Ltd | London | 2007 |
| Advetec International Ltd | Trowbridge | 2016 |
| Advetec North America Limited | Trowbridge | 2020 |
| Advice UN Limited | Swansea | 2014 |
| Advicecube Consultancy UK Ltd | Morden | 2022 |
| Adviser Platform Ltd | London | 2021 |
| Adviser Services Holdings Wealth Management Limited | Knutsford | 2023 |
| Adviseros Limited | London | 2014 |
| Adviseros Platform Limited | London | 2014 |
| Adviseros Trustee Company Limited | London | 2014 |
| Advisers Media International Limited | Burnley | 2001 |
| Advisory Holdings Ltd | Norwich | 2022 |
| Advisory Partners (UK) Limited | London | 2007 |
| Advistas Associates Ltd | Luton | 2012 |
| Advocate Contracts Limited | Belfast | 2013 |
| Advocate Homes Limited | Brigg | 2006 |
| Advocate Public Affairs Ltd | Belfast | 2013 |
| Advoco Financial Limited | Eastleigh | 2006 |
| Advokatconsult Ltd. | London | 2015 |
| Advotek Ltd | Stevenage | 2024 |
| Adwater Limited | Harrow | 2003 |
| Adwest Steering Ltd | Huddersfield | 2025 |
| Adxkom Limited | Stevenage | 2016 |
| ADY Engineering & Recycling Solutions Ltd | Birmingham | 2018 |
| AE (2013) Limited | Leeds | 2013 |
| AE Building & Landscaping Limited | Southwold | 2024 |
| AE Ocean Ltd | London | 2024 |
| AE Online Limited | Feltham | 2014 |
| AE Power Limited | Morecambe | 2018 |
| AE Roofing Ltd | Huntingdon | 2018 |
| AE Technical Limited | Banbury | 2014 |
| AE Tuition Limited | Twickenham | 2009 |
| Aebo Science Tech Co., Ltd | London | 2012 |
| Aebp Walling Limited | Kettering | 1985 |
| AEC Advance Electrical Contractors Limited | Kingston Upon Thames | 2012 |
| AEC Estate Consultants Limited | Rochford | 2026 |
| AEC Products Limited | London | 2006 |
| AEC Wind Ltd | Durham | 2019 |
| Aechoo Technology Co. Ltd | Beckenham | 2015 |
| AED Connect Limited | Bromborough | 2017 |
| Aedifico Nominee Limited | London | 2020 |
| AEG Decorating and Building Ltd | London | 2014 |
| AEG Portfolios Limited | Twickenham | 2012 |
| Aegean Atlas Ltd | London | 2026 |
| Aegean International Pool Supplies Limited | Horsham | 1987 |
| Aegean Maritime Limited | London | 2022 |