| ACS Fire and Security Limited | Portsmouth | 2007 |
| ACS Imaging Ltd | Sittingbourne | 2009 |
| ACS Industrial & Mechanical Engineering Services Ltd. | Swansea | 2013 |
| ACS Manufacturing & Supplies Ltd. | Leeds, | 2013 |
| ACS Plant Services Ltd | Retford | 2015 |
| ACS Print Ltd | Preston | 2019 |
| ACS Projects (London) Limited | Hertford | 2019 |
| ACS Stainless Limited | Leeds | 2015 |
| ACS Stainless Steel Fixings Limited | Leeds | 1984 |
| Acsent Innovation Enterprise Ltd | London | 2026 |
| Acsim Services Ltd | Bickley | 2003 |
| Acsys Lasertechnik UK Limited | Halesowen | 2012 |
| ACT (Accept, Challenge & Transform) Fitness Ltd | Pontyclun | 2019 |
| ACT Catering Ltd | Bristol | 2025 |
| ACT Cool Records Ltd | Barnet | 2022 |
| ACT Engineering Limited | Tonbridge | 2023 |
| ACT Group Technology Co., Limited | West Midlands, England | 2025 |
| ACT INT. Ltd. | Airdrie | 2009 |
| ACT Interiors Ltd | Aldershot | 2013 |
| ACT Meters (UK) Ltd | Southport | 2013 |
| ACT of Kindness Organics Ltd | Southsea | 2018 |
| ACT Performance Products Limited | Tonbridge | 2003 |
| ACT Products Limited | Stockton-On-Tees | 2009 |
| ACT Rail Ltd | Barnsley | 2026 |
| ACT Services & Repairs Ltd | Colchester | 2021 |
| ACT Tech Solutions Ltd | Loughton | 2025 |
| ACT UK Group (Fife) Limited | Tyne And Wear | 2022 |
| ACT UK Group Ltd | Hebburn | 2006 |
| ACT Universal Ltd | Aylesford | 2001 |
| Act-Put Limited | Orpington | 2017 |
| Act-Vst Limited | London | 2019 |
| Actask Fluid Control Limited | West Midlands, England | 2024 |
| Actatek Limited | London | 2007 |
| Actava Ltd | Belfast | 2025 |
| Actavis Holdings UK II Limited | Castleford | 1998 |
| Actavo (UK) Limited | Birmingham | 2000 |
| Actbold Limited | London | 1989 |
| Actbronze Limited | Loughborough | 1984 |
| Actcell Limited | London | 1976 |
| Actegy Limited | Bracknell | 2003 |
| Acteuro Limited | Mexborough | 2012 |
| Actgo Sports Limited | West Midlands, England | 2024 |
| Actheron (Dielife) Limited | Gosforth | 1984 |
| Actia (UK) Limited | Newtown | 1994 |
| Acticare Neuro Ltd | Bristol | 2023 |
| Acticheck Ltd | Fowlmere | 2014 |
| Actiform Limited | Mirfield | 1994 |
| Actifwear Limited | Market Harborough | 2008 |
| Actikem Ltd | Warrington | 2002 |
| Action 8 Components Limited | Newbury | 1995 |
| Action Absorbers Ltd | London | 2024 |
| Action Adhesives (UK) Limited | Saintfield | 2019 |
| Action Clad Limited | | 1977 |
| Action Creative Group Limited | Burgess Hill | 2012 |
| Action Electrics Limited | Hertford | 2014 |
| Action Engineering Ltd | Cumnock | 2025 |
| Action Engineering Services Ltd | Gravesend | 2025 |
| Action for Swifts Trading Ltd | Norwich | 2022 |
| Action Garage Midland Limited | Bilston | 2010 |
| Action Glass & Heritage Windows Limited | Sheffield | 2026 |
| Action Glass (U.K.) Limited | Chesterfield | 2005 |
| Action Graphics & Display Ltd | Redditch | 2019 |
| Action Handling Equipment Limited | Sawbridgeworth | 1970 |
| Action Leisurewear Limited | Hinckley | 2007 |
| Action Mailing Ltd | Accrington | 1997 |
| Action Mats Limited | Silsoe | 2016 |
| Action Office Interiors Ltd | Burgess Hill | 2012 |
| Action Plastics Ltd | Barnsley | 2018 |
| Action Play and Leisure Ltd | Carleton Rode | 2012 |
| Action Products (Bristol) Limited | South Gloucestershire | 2007 |
| Action Products Limited | South Gloucestershire | 1993 |
| Action Sports Studios Ltd | London | 2024 |
| Action TAG Ltd | Blackpool | 2006 |
| Action Tech Limited | Belfast | 2020 |
| Action Trading Ltd | Newmarket | 2010 |
| Actionfront Limited | Tipton | 1995 |
| Actiongovern Limited | Ashford | 1996 |
| Actionplas Limited | Pudsey | 1991 |
| Actiph Water Limited | Edinburgh | 2015 |
| Actiroam Ltd | Wrexham | 2025 |
| Activ Medical Disposables UK Ltd | London | 2018 |
| Activ Scientific Limited | London | 2022 |
| ACTIV8 Lubricants Limited | Lockerbie | 2002 |
| Activate for Kids Limited | Salisbury | 2015 |
| Activate Sense and Secure Limited | Halstead | 2019 |
| Activate Wear Ltd | Melksham | 2025 |
| Activated Oxygen Limited | Tamworth | 2000 |
| Activator Nutrition Limited | Birmingham | 2025 |
| Active 365 Group Limited | Oldham | 2023 |
| Active Air Products Ltd | Swansea | 2019 |
| Active Alloys Ltd | London | 2013 |
| Active Aluminium Systems Ltd | Manchester | 2011 |
| Active Auto Locksmith Limited | Potters Bar | 2025 |
| Active Autos UK Ltd | Sanquhar | 2020 |
| Active Carbon Filters Ltd | Birmingham | 2023 |
| Active Cleaningservices Ltd | Plymouth | 2013 |
| Active Controls Limited | Market Harborough | 2003 |
| Active Cooling & Airflow Services Limited | Peterborough | 2012 |
| Active Cosmetic Ingredients Ltd | Selby | 2011 |
| Active Covers Ltd | Cardiff | 2024 |