| Sarmin Consulting Limited | Aylesbury | 2006 |
| Sarn Helen Gold Ltd | Cardiff | 2019 |
| SAS Offshore Electrical Services Ltd | Buckie | 2018 |
| SAS Tech Mark Ltd | Aberdeen | 2024 |
| SAS Technical Ltd | Aberdeen | 2017 |
| Sasco Access Ltd | Kintail House | 2013 |
| Sasol UK Limited | London | 1989 |
| Saturnus Metals Ltd | London | 2020 |
| Savage Resource Limited | Manchester | 2012 |
| Savannah Advisory Services Limited | London | 2018 |
| Savannah Resources PLC | London | 2010 |
| Savarna Gems and Jewellery Ltd | London | 2025 |
| Sawana Steel Limited | Leicester | 2011 |
| Saxon OIL Limited | London | 1980 |
| Saxon OIL Miller Limited | London | 1996 |
| Saxonmoor Limited | Holmfirth | 1979 |
| Saxonmoor Quarry Limited | Holmfirth | 1960 |
| SB Drilling Engineering Limited | Aberdeen | 2023 |
| SB Quarry (Airdrie) Ltd | North Berwick | 2012 |
| SB Well Services Ltd | Montrose | 2014 |
| SBC Properties Limited | Stroud | 1985 |
| SBJ International Group Ltd | Harrow | 2024 |
| SC Mines Limited | Southampton | 2017 |
| SC Subsea Technical Services Limited | Downham Market | 2013 |
| SC Well Services Ltd | Montrose | 2023 |
| Scaravello Ltd | Montrose | 2011 |
| Scarborough Energy Limited | Leeds | 2022 |
| SCE Energy Limited | Aberdeen | 2017 |
| Schmidt International Chemical (UK) Ltd | Cambridge | 2025 |
| Schmidt Subsea Consulting Ltd | Staines-Upon-Thames | 2017 |
| Schoeller-Bleckmann Oilfield Equipment (UK) Limited | Chesterfield | 1996 |
| Science and Art Explorers Ltd | Newtownabbey | 2024 |
| Scientific Drilling Controls Limited | London | 1985 |
| SCJ Services Limited | Great Yarmouth | 2024 |
| SCK Holdings PVT Ltd | London | 2025 |
| Sclubb Ltd | Kingseat | 2026 |
| Scoh Inspection Limited | Billingham | 2011 |
| Scooby OIL & GAS Limited | Aberdeen | 2012 |
| Scopus Engineering Limited | Aberdeen | 1991 |
| Scot-Nor Services Ltd | Montrose | 2011 |
| Scotcoil Limited | Arbroath | 2000 |
| Scotmec Solutions Ltd | Peterhead | 2018 |
| Scots Pipeline Ltd | Carnoustie | 2014 |
| Scott Ferguson Services Ltd | Auchterarder | 2023 |
| Scott Service Engineers Ltd | Derry | 2012 |
| Scottmech Offshore Ltd. | Morpeth | 2013 |
| Scphg Ltd | Motherwell | 2025 |
| Scrap Local Ltd | Hollinwood | 2019 |
| Scythian Mining Group Limited | London | 2017 |
| Scythian OIL Ltd | London | 2013 |
| SDL Nobel Limited | London | 2000 |
| Sdmra Limited | Great Yarmouth | 2022 |
| SDS E&P Ltd. | London | 2017 |
| Sduncan Ltd | Macduff | 2024 |
| SDX Energy Holdings (UK) Limited | London | 2019 |
| SDX Energy Limited | London | 2019 |
| SDX Energy Morocco (UK) Limited | London | 2016 |
| Sea Diver Ltd | Macduff | 2022 |
| Sea JET Systems Limited | Great Yarmouth | 2022 |
| Sea Lion (Devon) Ltd | Bideford | 2017 |
| Sea Salt Hebrides Ltd | Isle Of North Uist | 2022 |
| Sea Sparks Ltd | Saltcoats | 2014 |
| Sea Technology OIL Refining Mining & Energy Limited | Peterborough | 2024 |
| Sea Thomson Ltd | Ullapool | 2014 |
| Sea-Bed Solutions Limited | Wolverhampton | 2012 |
| Seacableconsultants Limited | Newport | 2015 |
| Seacrest Petroleo UK Limited | Clapham | 2023 |
| Seadrill Management Ltd. | Liverpool | 2012 |
| Seadrill UK Operations Ltd | Aberdeen | 1993 |
| Seagull Petroleum and Mining Limited | London | 2018 |
| Seagull Resources Ltd | London | 2022 |
| Seahorse OIL Field Services Ltd | London | 2023 |
| Seal Coordinations Ltd | Billingham | 2025 |
| Sealmor Ltd | Peterhead | 2025 |
| Seamus Grogan Ltd | Omagh | 2023 |
| Sean Holebrook Company Ltd. | Callington | 2018 |
| Searay(Scot) Ltd | Peterhead | 2025 |
| Search Team Limited | Shipston On Stour | 2009 |
| Seas Master Ltd | Manchester | 2022 |
| Seascape Energy (Dewa) Limited | London | 2024 |
| Seasouth Mining and Quarrying Ltd | Leigh-On-Sea | 2024 |
| Seaweld Services UK Ltd | Greenhithe | 2017 |
| Sea\Lng Limited | Glasgow | 2016 |
| SEB Consultants Ltd | Peterhead | 2025 |
| SEC Excavations Ltd | Halifax | 2026 |
| Sectormetric Ltd | London | 2025 |
| Security Deposits Limited | Leeds | 2006 |
| Seddon Geophysical Limited | London | 2017 |
| Sedimentix Limited | Llandudno | 2018 |
| Seek OIL & GAS Services Limited | Great Yarmouth | 2023 |
| Seghill Bolting Ltd | Cramlington | 2024 |
| Seiont Limited | Ruthin | 2016 |
| Seis Solutions Ltd | Bradford | 2010 |
| Seiscon Limited | Glenrothes | 2006 |
| Seisconnexions Associates Ltd | Grays | 2025 |
| Seismarque Ltd | London | 2019 |
| Seistech Energy Limited | Dunstable | 2021 |
| Seleg Services Limited | London | 2025 |
| Self Reliance Ltd | Leicester | 2021 |
| Selkirk Welding Services Limited | Ashington | 2016 |