| Active Winter Services Ltd | Mansfield | 2025 |
| Active Workforce Solutions Ltd | Norwich | 2022 |
| Active-Rest Ltd | Esher | 2019 |
| ACTIVE24/7 Security UK Ltd | Felixstowe | 2012 |
| ACTIVE8 Communities Ltd | Leighton Buzzard | 2023 |
| ACTIVE8 Managed Technologies (Silverstone) Ltd | Newark | 2020 |
| ACTIVE8EVENTS (UK) Limited | Penrith | 2001 |
| Activecaring Ltd | Nottingham | 2022 |
| Activedance Spirals Ltd | Bolton | 2012 |
| Activefootprint Limited | Farnborough | 2011 |
| Activeguard Monitoring Limited | Pontypridd | 2015 |
| Activeguardian Ltd | Fitzrovia | 2024 |
| ACTIVEK9SECURITY Ltd | Wakefield | 2022 |
| Actively Chilled Ltd | London | 2020 |
| ACTIVEO3 Ltd | Chichester | 2024 |
| Activepada Limited | London | 2020 |
| Activepage Strategy Limited | Northwich | 2010 |
| Actives Support Ltd | London | 2023 |
| Activescapes Ltd | Folkestone | 2025 |
| Activeselect Limited | Watford | 2024 |
| Activetra Group Ltd | London | 2019 |
| Activeway Estates Ltd | London | 2004 |
| Activexplore Travel Ltd | Polegate | 2024 |
| Activist Group Limited | Milton Keynes | 2008 |
| Activist Talent Ltd | Manchester | 2020 |
| Activities 115 | Kingsbridge | 2000 |
| Activities Abroad Limited | North Shields | 2004 |
| Activity Bookings Ltd | London | 2025 |
| Activity Box Limited | Wokingham | 2002 |
| Activity Club Coventry Limited | Coventry | 2011 |
| Activity Crest Limited | Oldbury | 2024 |
| Activity Linker Ltd | London | 2022 |
| Activity Supplies Limited | Birmingham | 2024 |
| Activity Wales Limited | Pembrokeshire | 1992 |
| Activity Yachting Ltd | Mirfield | 2025 |
| Activium Finance Ltd | London | 2017 |
| Activo Group Limited | Kingston Upon Thames | 2023 |
| Activtransport Limited | Belfast | 2021 |
| Activus Recruitment Limited | Oldmeldrum | 2012 |
| Actiwise Limited | Cambridge | 2009 |
| Actmore-Psm Limited | London | 2019 |
| Actnow Services Ltd | Westerham | 2023 |
| Acton Banks Limited | Wolverhampton | 2006 |
| Acton BID Company Limited | London | 2019 |
| Acton Design Partnership Limited | Stafford | 2008 |
| Acton Locksmiths Limited | London | 2003 |
| Acton Marquees Limited | Northwich | 2010 |
| Acton Relocation Management Ltd | Stafford | 2013 |
| Acton Ridge Ltd | Stafford | 2012 |
| Acton UK Management Ltd | Rochdale | 2011 |
| Acton Ventures Limited | Coventry | 2011 |
| Actorbank Ltd | St Ives | 2013 |
| Actorcard.Com Limited | Manchester | 2015 |
| Actors Pro Expo Ltd | London | 2010 |
| Actors World Production Limited | | 1982 |
| Actorsgarden Limited | Edgware | 2017 |
| Actotum Limited | Cardiff | 2019 |
| Actovation Limited | Ballymena | 2001 |
| Actpr Ltd | York | 2009 |
| Actrav Limited | Perth | 2009 |
| Actrov Ltd | Warrington | 2021 |
| Actsafe Training Services Limited | Waterlooville | 2025 |
| Actsmart Global Ltd | London | 2025 |
| Actu - 8 Solutions Ltd | London | 2010 |
| Actu Property Group Limited | Enfield | 2021 |
| ACTU8 (Thps) Ltd | Newcastle Upon Tyne | 2015 |
| Actua Risk Limited | Wimborne | 2003 |
| Actual Assist Limited | Edinburgh | 2019 |
| Actual Limited | Carlisle | 2025 |
| Actual Solutions (UK) Limited | Weybridge | 1997 |
| Actual Staff Ltd | Cardiff | 2024 |
| Actual Staffing Ltd | Cardiff | 2022 |
| Actualcare Ltd | Walsall | 2012 |
| Actualise Business Consultancy Ltd | Watford | 2013 |
| Actualise Design Ltd | Colchester | 2012 |
| Actuality Group Ltd | London | 2017 |
| Actuality One Limited | Glasgow | 2010 |
| Actualize Business Solutions Ltd | Appleton Thorn | 2011 |
| Actualize Promotions Ltd | Retford | 2022 |
| Actualpay Solutions Ltd | London | 2024 |
| Actuarial Marketplace Ltd | Portstewart | 2024 |
| Actuaries for Lawyers Limited | Wiltshire | 2003 |
| Actuated Valve Supplies Ltd | Worcester | 2016 |
| Actus HR Limited | Tonbridge | 2024 |
| Actus Industries Limited | Maidenhead | 2008 |
| Actus Recruitment Group Ltd | London | 2025 |
| Actv-Uk Ltd | Crediton | 2017 |
| Actx Solutions Ltd | Romford | 2022 |
| ACU Commercial Limited | Barnsley | 2017 |
| ACU Trading Ltd | London | 2014 |
| Acu-Synergy Limited | London | 2015 |
| Acucoaching Services Ltd | Ruislip | 2016 |
| Acuerdo Recruitment Limited | London | 2022 |
| Acuitas Executive Search & Advisory Limited | Cardiff | 2015 |
| Acuity & Acumen Solutions Limited | London | 2016 |
| Acuity Energy Solutions Limited | Redhill | 2017 |
| Acuity Environmental Services Ltd | Cradley Heath | 2016 |
| Acuity Estates Ltd | Frome | 2011 |
| Acuity HR Limited | Halesowen | 2023 |
| Acuity Professional Business Performance Coaching Limited | Bexhill | 2015 |