| Added Dimension Events Limited | Tadley | 1995 |
| Added Security Systems Ltd | March | 2024 |
| Added Value Marketing Limited | Bushey Heath | 2010 |
| Added Value Services (East Anglia) Ltd | Emneth | 2010 |
| Addeen Tours Limited | Leicester | 2023 |
| Addeley Holdings Limited | London | 2011 |
| Addelice Limited | Birmingham | 2008 |
| Adder Business Ltd | Inverness | 2018 |
| Adder Investment Holdings | Dumbarton | 2009 |
| Adder Machine Services Limited | Nuneaton | 2008 |
| Adder Security Ltd | Stockton-On-Tees | 2014 |
| Adderley Featherstone Limited | Cardiff | 1991 |
| Adderley Riverside Management Company Limited | London | 2017 |
| Adderstone Mains Management Company Limited | Nr Belford | 2005 |
| Addewid CYF | Caernarfon | 2025 |
| Addex Resource Limited | Dundee | 2023 |
| Addfarn Limited | Burton-On-Trent | 1992 |
| Addguests Ltd | London | 2021 |
| Addhire Self Drive Limited | Chester | 1990 |
| Addicorp Limited | Warrington | 2013 |
| Addict Cleaners Limited | Derby | 2025 |
| Addict Holdings Limited | London | 2009 |
| Addicted Films Limited | Westerham | 2006 |
| Addicted to Clean Ltd | Marlow | 2023 |
| Addicted to Jesus Ltd | Manchester | 2022 |
| ADDICTED2ADVENTURES Ltd | Aylesbury | 2018 |
| ADDICTED2CLEANING Ltd | London | 2025 |
| Addiction Hub Limited | Chesterfield | 2025 |
| Addiction Recovery Systems Limited | Dalry | 2018 |
| Addiction to Detail Limited | Nottingham | 2016 |
| Addictive Adventure Ltd | Inverness | 2023 |
| Addictive Audio Ltd | Cleckheaton | 2023 |
| Addidi Holdings Nominee Limited | Reading | 2018 |
| Addie Gardner-Williams Limited | London | 2025 |
| Addiem VA Limited | Maidenhead | 2023 |
| Addiewell Prison Ltd | Aberdeen | 2005 |
| Addimus Limited | Guildford | 2012 |
| Addinall HR and Mediation Limited | Norwich | 2024 |
| Adding Knowledge Limited | Birmingham | 2015 |
| Adding Oxygen Limited | Beverley | 2012 |
| ADDING2IT Limited | Kettering | 2005 |
| Adding:Tours Emea Limited | London | 2025 |
| Addington Ball Recruitment Limited | Kenilworth | 2011 |
| Addington Development Company Limited | Warwick | 2017 |
| Addington Group Limited | London | 2018 |
| Addington Partners Limited | London | 2020 |
| Addington Plant Services Limited | London | 2016 |
| Addingvalue Ltd | Manchester | 2010 |
| Addis Link Limited | | 2003 |
| Addis Project Management Ltd | Swindon | 2012 |
| Addis Rental Ltd | London | 2025 |
| Addiscombe Road Ltd. | Hemel Hempstead | 2026 |
| Addiscombe UK Limited | Croydon | 2021 |
| Addiscombe Villa RTM Company Limited | Hampton Hill | 2014 |
| Addison Electrical Limited | Forfar | 2000 |
| Addison Gardens Management Company Newbury Ltd | Reading | 2018 |
| Addison HR Consulting Ltd | London | 2025 |
| Addison Hunt Ltd | Leicester | 2016 |
| Addison Johnston Limited | South Croydon | 2014 |
| Addison LEE Enterprises PVT Ltd | Amersham | 2025 |
| Addison Maxwell Limited | London | 2017 |
| Addison Plus Ltd | Aylesbury | 2014 |
| Addison Property Management Ltd | Romford | 2023 |
| Addison Travel Limited | Manchester | 1992 |
| Addison-Ross Limited | Berwick-Upon-Tweed | 2008 |
| Addisons Fire and Security Limited | Dalton | 2026 |
| Additae Ltd | Preston | 2017 |
| Additech Ltd | Cheadle Hulme | 2006 |
| Addition International Limited | Maidenhead | 2006 |
| Addition Limited | Sheffield | 2009 |
| Addition Solutions Ltd | Letchworth Garden City | 2012 |
| Additional Care Ltd | Ilford | 2019 |
| Additional Intelligence Group Ltd | Morden | 2025 |
| Additional Recruitment Limited | London | 2018 |
| Additional Resources Limited | Doddinghurst Road, Brentwood | 1999 |
| Additional Security Ltd | Blackburn | 2021 |
| Additional Services Ltd | Tonbridge | 2020 |
| Additions Logistics Ltd | Woodbridge | 2024 |
| Additri Limited | London | 2018 |
| Addivinity Limited | London | 2010 |
| Addler Limited | Barnet | 2016 |
| Addleshaw Booth & Co. Service Company | London | 1996 |
| Addlestone Car Valeting Ltd | Addlestone | 2025 |
| Addlist Limited | Covent Garden | 2021 |
| Addmore UK Ltd | Dagenham | 2015 |
| Addo & Addo Limited | Kettering | 2022 |
| Addo Consulting Limited | Stoke-On-Trent | 2014 |
| Addo Pinhoe Ltd | Exeter | 2020 |
| Addor Systems Limited | Torquay | 2023 |
| Addowls Productions Ltd | London | 2026 |
| Addo’S Domestic Services Limited | London | 2025 |
| Addpay Ltd | Romford | 2026 |
| Addplant Limited | East Yorkshire | 1984 |
| Address Logic Ltd | Chipping Norton | 2015 |
| Address Properties Limited | Liverpool | 2012 |
| Address Property Consultants Limited | London | 2012 |
| Addrestic Limited | Maldon | 2023 |
| Addspace Limited | Clevedon | 1999 |
| Addstack Limited | Wickford | 1989 |
| Addtime Recording Company Limited | St. Helens | 1989 |