| Active Qcross Ltd | London | 2025 |
| Active Reality Ltd | Bath | 2019 |
| Active SEO Consultants Limited | Newcastle Upon Tyne | 2024 |
| Active Slim Limited | Bournemouth | 2010 |
| Active Software Platform UK Ltd | Maidenhead | 2023 |
| Active Solutions (Windsor) Limited | Windsor | 2017 |
| Active Solutions Limited | Clitheroe | 1987 |
| Active Sonic Technologies UK Limited | Northwood | 2024 |
| Active Space Listening Ltd | London | 2024 |
| Active Steward Limited | Bridlington | 2015 |
| Active TC Limited | Westcliff-On-Sea | 2025 |
| Active Telecoms Limited | Kings Lynn | 2003 |
| Active Thread Ltd | Newport | 2002 |
| Active Toolkit Limited | Crewe | 2015 |
| Active TV Aerials Limited | Sutton | 2009 |
| Active Vertex Ltd | London | 2022 |
| Active Voices Limited | Isleworth | 2022 |
| Active Webdezign Ltd | Middlesex | 2000 |
| Active Websites Limited | Hampshire | 2004 |
| Active Wills Limited | Market Drayton | 2011 |
| Active Workspace Limited | Chelmsford | 1990 |
| ACTIVE550 Limited | London | 2011 |
| ACTIVE8 Managed Technologies (London) Ltd | Newark | 2014 |
| ACTIVE8 Managed Technologies IT Ltd | Newark | 2010 |
| Activeai LAB Limited | London | 2025 |
| Activeayesh Ltd | Gosport | 2024 |
| Activebiz Information Systems Limited | Solihull | 2012 |
| Activecore Limited | Altrincham | 2021 |
| Activedots Ltd | Mildenhall | 2026 |
| Activefence Limited | London | 2022 |
| Activefx Limited | Wallington | 2013 |
| Activegen Limited | London | 2023 |
| Activeis Limited | Barnet | 1997 |
| Activeit Project Consultants Limited | West Byfleet | 2025 |
| Activelab Limited | Liverpool | 2007 |
| Activeledger & NITR0GEN Tech Limited | London | 2023 |
| Activelyoutdoors Ltd | Sale | 2018 |
| Activemanage Ltd. | Basford | 2016 |
| Activemate Limited | Swansea | 2020 |
| Activenet Data Solutions Ltd. | Watton | 2000 |
| Activenet Solutions Limited | Burton Ontrent | 2013 |
| Activenture Ltd | London | 2024 |
| Activeops Overseas Limited | Reading | 2010 |
| Activeops PLC | Reading | 1995 |
| Activeplan Consulting Limited | Nottingham | 2009 |
| Activeplan Retail Limited | Derby | 2017 |
| Activepoint UK Limited | Leeds | 2013 |
| Activequine Limited | Heanor | 2019 |
| Activequote Limited | Cardiff | 2008 |
| Activescan Limited | Belfast | 2023 |
| Activesoft Ltd | London | 2026 |
| Activespace Limited | London | 2018 |
| Activest Ltd | London | 2021 |
| Activesync Ltd | Hockley | 2026 |
| Activeviam Ltd | London | 2005 |
| Activevoice Store Ltd | Mansfield | 2024 |
| Activewebdevelopers Limited | Bembridge | 1996 |
| Activexchange Ltd | Milton Keynes | 2020 |
| Activideo Communications Limited | Macclesfield | 2002 |
| Activisehealth Ltd | St. Neots | 2026 |
| Activision Blizzard Media Limited | London | 2016 |
| Activision Blizzard UK Ltd | London | 1983 |
| Activit Consulting Ltd | Watford | 2018 |
| Activities R US | London | 2014 |
| Activitus Limited | Walton On Thames | 2026 |
| Activity Cloud Ltd | Winscombe | 2012 |
| Activity Mapper Ltd | Drakelow | 2025 |
| Activity Publishing Limited | Pulborough | 2025 |
| Activity Score Limited | Newcastle Upon Tyne | 2024 |
| Activityid Ltd | Aberdeen | 2021 |
| Activitypal Ltd | London | 2014 |
| Activitypro Limited | Croydon | 2017 |
| Activixx Ltd | London | 2024 |
| Activnet Ltd | Worcester | 2014 |
| Activo Consulting UK Limited | London | 2025 |
| Activote Ltd | London | 2023 |
| Activpayroll Ltd. | Aberdeen | 1999 |
| Activplay Limited | Rossendale | 2014 |
| Activpoints UK Limited | Kington | 2014 |
| Actix Limited | London | 1991 |
| Actnow House Ltd | Newbury | 2019 |
| Actogram Ltd | London | 2023 |
| Acton a Advisory Limited | London | 2014 |
| Acton Consulting Ltd | Chelmsford | 2020 |
| Acton Digital Limited | Totnes | 2017 |
| Acton Edocs Systems Ltd | Wrexham | 2019 |
| Acton Gate Systems Limited | Wolverhampton | 2001 |
| Acton Green Music Limited | London | 1974 |
| Acton Web Services Ltd | Wrexham | 2022 |
| Actonomous Ltd | Reading | 2026 |
| Actopia Communications Limited | Milton Keynes | 2010 |
| Actora Ltd | Milton Keynes | 2025 |
| Actorflow Ltd | London | 2025 |
| Actoriax Discovery Ltd | Birmingham | 2026 |
| Actorize Limited | Swansea | 2024 |
| Actors Ready SET Go CIC | London | 2025 |
| Actors Studio Ltd | Slough | 2023 |
| Actosa Limited | Herts | 2005 |
| Actr-Ai Limited | London | 2024 |
| Actrix Financial Technology Ltd | London | 2024 |