| ENI UK Limited | London | 1965 |
| ENI ULX Limited | London | 1968 |
| ENI Uruguay Limited | London | 2025 |
| ENI West Ganal Limited | London | 2019 |
| ENI West Timor Limited | London | 2008 |
| ENI Yemen Limited | London | 2005 |
| Enneco Ltd | Aberdeen | 2020 |
| Enquest Britain Limited | London | 1998 |
| Enquest Dons Leasing Limited | London | 2011 |
| Enquest ENS Limited | London | 2007 |
| Enquest EP BV Limited | London | 2025 |
| Enquest EP Gaea II Limited | London | 2025 |
| Enquest EP Gaea Limited | London | 2025 |
| Enquest Global Limited | London | 2013 |
| Enquest Heather Leasing Limited | London | 2011 |
| Enquest Heather Limited | London | 1992 |
| Enquest Marketing and Trading Limited | London | 2014 |
| Enquest NWO Limited | London | 2013 |
| Enquest Petroleum Production Malaysia Ltd | London | 2013 |
| Enquest PLC | London | 2010 |
| Enquest Production Limited | London | 1971 |
| Enquest Progress Limited | London | 2002 |
| Enrc Africa Holdings Limited | London | 2001 |
| Enrgy Resources Ltd | Glasgow | 2008 |
| Ensco 1340 Limited | Swadlincote | 2019 |
| Ensco Deepwater Drilling Limited | London | 2013 |
| Ensco Offshore U.K. Limited | London | 1993 |
| Ensco Services Limited | London | 2002 |
| Ensco U.K. Limited | London | 2002 |
| Ensco UK Drilling Limited | London | 2017 |
| Ensco Universal Limited | London | 2009 |
| Enterprise OIL Limited | London | 1982 |
| Enterprise OIL Middle East Limited | London | 1991 |
| Enterprise OIL Norge Limited | London | 1982 |
| Enterprise OIL U.K. Limited | London | 1988 |
| Enventure International (UK) Limited | Aberdeen | 2018 |
| Enviroaggs Limited | Beverley | 2021 |
| Enviromec Limited | Ottery St Mary | 2000 |
| Enviromine Limited | Upton | 2013 |
| Environmental Pipeline Services Limited | Dunstable | 2008 |
| Environmental Processing Solutions Limited | Bristol | 2016 |
| Environstore Limited | Westhill | 2006 |
| Envisioglobal Ltd | Prescot | 2017 |
| Envoi Limited | London | 1999 |
| Enwell Energy PLC | London | 2002 |
| EOM Tech Ltd | Peterhead | 2017 |
| Eone International Ltd | London | 2002 |
| EOS Energies Limited | Leigh-On-Sea | 1999 |
| EOS Technix Limited | Aberdeen | 2018 |
| EOW and Company UK Limited | Streatham | 2019 |
| EPC United Kingdom Limited | Alfreton | 1905 |
| Epideme Systems Limited | Egham | 2008 |
| Epidote Holdings Limited | Aberdeen | 2012 |
| Eppleton Quarry Products (Middlesbrough) Ltd | Rushyford | 2003 |
| Eppleton Quarry Products (Scunthorpe) Limited | County Durham | 2002 |
| Eppleton Quarry Products Limited | Ferryhill | 2001 |
| Eprocess Technologies Ltd | Truro | 2012 |
| Epsilon Energy Solutions Ltd | Aberdeen | 2018 |
| EQ Petroleum Sabah Ltd | London | 2010 |
| Equanimity Drilling Ltd | Prestwick | 2018 |
| Equator Gold Limited | Salisbury | 2011 |
| Equinor UK Limited | London | 1976 |
| Equinor WOS Limited | London | 1970 |
| Equion Energia Limited | London | 1959 |
| Equipaxxess Limited | Bournemouth | 2003 |
| Equus Petroleum Limited | London | 2011 |
| ER274 Limited | Oxford | 2025 |
| Eragon Petroleum Limited | London | 2007 |
| ERC Equipoise Limited | Lingfield | 1998 |
| Erdis Nigeria (UK) Ltd | London | 2021 |
| Erebus Investments Limited | Marlow | 2008 |
| ERG Engineering Limited | Norwich | 2013 |
| ERG Industrial Ltd | Ripon | 2025 |
| Eruptive Materials Ltd | London | 2022 |
| Ervr Services Ltd | Elgin | 2024 |
| Erwin Peat Ltd | Craigavon | 2011 |
| Esanda Engineering Limited | London | 2006 |
| Esen Mining Consulting Services UK Ltd | London | 2022 |
| ESG Prosperity Ltd | Tadworth | 2021 |
| ESK Offshore Limited | | 1998 |
| Eskdale Stone Limited | Whitby | 1996 |
| Eskra Quarries Ltd | Omagh | 2019 |
| Eskwell Services Ltd | Montrose | 2004 |
| Esnad Africa OIL Operations UK Limited | Grimsby | 2023 |
| ESP Expertise Limited | Coventry | 1999 |
| ESP Safety Scotland Limited | Edinburgh | 2023 |
| Esperanza Logistics Limited | London | 2020 |
| Esperanza Resources Limited | London | 2020 |
| Esprit Petroleum Limited | Gourock | 2014 |
| Esptech Ltd | Forfar | 2016 |
| Essch Engineering Ltd | Fraserburgh | 2019 |
| Esso Exploration and Production UK Limited | Fawley | 1925 |
| Este Medical Group East London & Liverpool ST Ltd | London | 2019 |
| Estepan Consulting Gubernamental Ltd | London | 2017 |
| Estornino Fishing Limited | Kingston Upon Thames | 1992 |
| Estuary Fuel Oils Limited | Caldicot | 2020 |
| Estuary Fuels Limited | Caldicot | 2020 |
| Etanoil Limited | | 2007 |
| Ethos Minerals Limited | Loughton | 2024 |
| Eurang Limited | Kingston-Upon-Thames | 2007 |