| ACTION4 Limited | Reading | 1997 |
| Actions 4 Learning Difficulties Limited | London | 2019 |
| Actions Against Climate Change Ltd | London | 2022 |
| Actis Global Ltd | Slough | 2023 |
| Actis SNC Limited | London | 2021 |
| Actium Occasions Limited | Orpington | 2019 |
| Activ First Limited | Doncaster | 2009 |
| Activ Project Management Limited | Manchester | 2016 |
| ACTIV8 Energies UK Limited | Guildford | 2024 |
| ACTIV8 Fitness & Nutrition Ltd | Benfleet | 2023 |
| Activate B. D. Limited | Northampton | 2009 |
| Activate Body & Mind Community Activities C.I.C. | Liverpool | 2022 |
| Activate Collective Ltd | London | 2024 |
| Activate Your Life | Preston | 2008 |
| Active Acuherb Ltd | London | 2022 |
| Active Aims Limited | Loughborough | 2002 |
| Active Always Community Wellbeing CIC | Worcester | 2022 |
| Active Asbestos Management Ltd | Bideford | 2022 |
| Active Aware Engaged Psychology Therapy and Consultancy Services Limited | York | 2022 |
| Active Balance Consultancy (NE) Limited | Hartlepool | 2018 |
| Active Black Country Limited | Halesowen | 2022 |
| Active Body Clinic Ltd | Billericay | 2013 |
| Active Body Osteopathy Limited | St. Albans | 2024 |
| Active Care Plus Ltd | Rotherham | 2016 |
| Active Choice Solutions Ltd | Manchester | 2021 |
| Active Claims (UK) Ltd | Bradford | 2006 |
| Active Cleaning Holiday Homes Limited | Plymouth | 2016 |
| Active Clinics Ltd | Birmingham | 2018 |
| Active Coach Limited | Stevenage | 2021 |
| Active Community Engagement Limited | Chester | 2008 |
| Active Constructions Ltd | Manchester | 2013 |
| Active Digital Media Ltd | Cheshire | 2001 |
| Active Dog Academy Ltd | Cirencester | 2023 |
| Active Dog Essentials Limited | Banbury | 2024 |
| Active Dog Limited | London | 2011 |
| Active Domestic Appliances Ltd | Reading | 2012 |
| Active Energy Advisers NW Ltd | Bristol | 2022 |
| Active Equestrian Ltd | Chalfont | 2011 |
| Active Fakenham Ltd | Fakenham | 2012 |
| Active Fire Services Ltd | Ilford | 2021 |
| Active Fire Systems Ltd | Chertsey | 2022 |
| Active Fit Ltd | Cardiff | 2018 |
| Active Friendly Support Limited | Sheffield | 2017 |
| Active Fuels Limited | Chelmsford | 2013 |
| Active Health Personal Training and Life Coaching Limited | 70 High Street, Fareham | 2004 |
| Active Health Wrexham Ltd | Coedpoeth | 2015 |
| Active Hearts and Minds Limited | Mildenhall | 2024 |
| Active House Alliance (UK Chapter) Ltd | Glenrothes | 2022 |
| Active Humanity Ltd | Birmingham | 2025 |
| Active Independence | Doncaster | 2012 |
| Active Indoor Leisure Association Limited | Redruth | 2022 |
| Active Introductions Limited | London | 2020 |
| Active Lancashire Limited | Leyland | 2009 |
| Active Legends Limited | London | 2023 |
| Active Life Therapy Ltd | Manchester | 2018 |
| Active Listening | Ballymena | 2010 |
| Active Live Services Ltd | Dinorwig | 2025 |
| Active Management Corporation Limited | Wrexham | 2019 |
| Active Management Services Limited | Sheffield | 1980 |
| Active Mobile Tyre Ltd | Wembley | 2021 |
| Active Mortgage Co. Limited | Maldon | 2008 |
| Active Paws Ltd | Chalfont St Giles | 2015 |
| Active Performance UK Ltd | Stamford | 2018 |
| Active Physio Limited | Nottingham | 2013 |
| Active Pro Ltd | Doncaster | 2013 |
| Active Pump Services Ltd | Worthing | 1998 |
| Active Recovery Limited | Wisbech | 1997 |
| Active Revival Ltd | Tonbridge | 2025 |
| Active Roses Ltd | Blackburn | 2019 |
| Active SCG Limited | East Sussex | 2004 |
| Active Shift Limited | London | 2025 |
| Active Solutions Engineering Limited | Blackburn | 2018 |
| Active Stirling Trading Limited | Stirling | 2007 |
| Active UK Marketing Ltd | London | 2014 |
| Active Weed Control Limited | Stafford | 1999 |
| Active With Alexandra Ltd | Hemel Hempstead | 2021 |
| Active X Clinics Ltd. | Edinburgh | 2003 |
| Active X Osteopaths Ltd. | Edinburgh | 2003 |
| Active X Physiotherapy Ltd. | Edinburgh | 2003 |
| ACTIVE8 IT Limited | Peterborough | 2005 |
| Activealldayfitness Ltd | Harlow | 2025 |
| Activebeing Limited | Bristol | 2021 |
| Activebookings.Com Ltd | Rochdale | 2025 |
| Activecare OT Limited | Tipton | 2024 |
| Actively Alive Limited | Faversham | 2021 |
| Actively Transforming Youth & Community | Newtownards | 2015 |
| Activereach Ltd | Cowdenbeath | 2024 |
| Activeskills Recruitment Ltd | Essex | 2024 |
| Activetrend Limited | Manchester | 1989 |
| Activewise Limited | Mold | 1986 |
| Activities for Improved Mood (AIM) Community Interest Company | Skelmersdale | 2022 |
| Activity Gift Vouchers Limited | Westerham | 1998 |
| Activity Pembrokeshire Limited | Haverfordwest | 2017 |
| Activity Van Designs Ltd | Leyland | 2019 |
| Activmobs CIC | St Austell | 2010 |
| Actlodge Limited | Essex | 2004 |
| Actmar Ltd | Wolverhampton | 2019 |
| Acton Actuarial Limited | Newbury | 2024 |
| Acton Barbers Ltd | London | 2023 |
| Acton Beauty Ltd | London | 2018 |