| SM Hire (Cumbria) Ltd | Administrative & support | 2024 |
| SM Innovate Limited | Professional & scientific | 2024 |
| Smallcapital Limited | Construction | 2009 |
| Smart Blinds UK Limited | Wholesale & retail | 2008 |
| Smart CUT Carlisle Ltd | Other services | 2022 |
| Smart Getaways Ltd | Hospitality | 2023 |
| Smart Home Innovations LLP | | 2013 |
| Smarter Offices Ltd | Transport & logistics | 2016 |
| Smartfit Windscreens Ltd | Wholesale & retail | 2022 |
| SMB Site Services Limited | Construction | 2014 |
| SMC Engineering Consultancy Ltd | Manufacturing | 2013 |
| Smile Fast Ltd | Health & social care | 2012 |
| Smilefast Implants Ltd | Education | 2021 |
| Smilefast Implants Training Ltd | Education | 2021 |
| Smith Recruitment Limited | Administrative & support | 2018 |
| Snaefell P a R Limited | Construction | 2025 |
| Snipelaw Limited | Professional & scientific | 2007 |
| Snowdale Holiday Lettings LLP | | 2022 |
| Snowdale Properties Ltd | Real estate | 2021 |
| Sobo Limited | Households | 2026 |
| Sockbridge Management Limited | Households | 1973 |
| Sofia Medical Services Limited | Health & social care | 2024 |
| Solan Limited | Extraterritorial | 2018 |
| Solar Lounge Northumbria Limited | Manufacturing | 2019 |
| Solar Maintenance Services Limited | Construction | 2015 |
| Solo Cafe Bars Limited | Real estate | 2003 |
| Solocare 2021 Unlimited | Administrative & support | 2021 |
| Solrail Ltd | Arts & recreation | 2012 |
| Soltic PVT Ltd | Professional & scientific | 2026 |
| Solway Building Solutions Limited | Construction | 2019 |
| Solway Developments Ltd | Construction | 2025 |
| Solway Direct Limited | Water & waste | 2005 |
| Solway Graphics Limited | Professional & scientific | 2018 |
| Solway Group International Ltd | Manufacturing | 2020 |
| Solway Light Aviation Limited | Arts & recreation | 1998 |
| Solway Pilotage & Maritime Services LLP | | 2024 |
| Solway Plastering and Tiling Limited | Construction | 2016 |
| Solway Shrimping Company Limited | Wholesale & retail | 2026 |
| Solway Slate & Tile Co. Ltd | Wholesale & retail | 1996 |
| Somerset House (Duke Street) Management Company Limited | Households | 2013 |
| Sonatas Hair Design Limited | Other services | 2006 |
| Sonentials Limited | Wholesale & retail | 2023 |
| Sonmezler Property Ltd | Real estate | 2025 |
| Sonos Omnes Ltd | Information & communication | 2020 |
| Sophie Waugh Properties Ltd | Real estate | 2016 |
| Sophistiqué Beauty Specialists Ltd | Other services | 2025 |
| Sosi 86 Limited | Transport & logistics | 2016 |
| Sotto Ltd | Hospitality | 2015 |
| Soul Retrieval Ltd | Information & communication | 2024 |
| Soul Suite (Workington) Limited | Hospitality | 2017 |
| Soumyasurith Ltd | Health & social care | 2024 |
| Sound & Light Solutions Limited | Wholesale & retail | 2004 |
| South Devon Herd Book Society(The) | Administrative & support | 1891 |
| South Lakes Firewood Ltd | Construction | 2019 |
| South Vale Court Management Company Limited | Households | 2021 |
| South View Farm Properties Limited | Real estate | 2023 |
| Southwell Services Ltd | Construction | 2026 |
| Southwells Bedrooms Ltd | Manufacturing | 2016 |
| Southwells Chimney and Stove Services Ltd | Administrative & support | 2018 |
| Southwells Chimney Systems Ltd | Construction | 2018 |
| Southwells Installations Limited | Manufacturing | 2015 |
| Southwells Interiors Ltd | Construction | 2023 |
| Southwells Properties Ltd | Construction | 2020 |
| Southwells Stove Installations Ltd | Administrative & support | 2018 |
| Southwells Trade Limited | Manufacturing | 2016 |
| Sowerby Estates Limited | Real estate | 2025 |
| Sowerby Wood Lettings Limited | Hospitality | 2013 |
| SP I&C Services Ltd | Professional & scientific | 2024 |
| SP Parcels & Packages Ltd | Transport & logistics | 2025 |
| SP Training Limited | Education | 2016 |
| Spadeadam Motor Club Limited | Arts & recreation | 1992 |
| Sparkle Like a GEM Ltd | Administrative & support | 2026 |
| SPC Manchester Limited | Health & social care | 2017 |
| Special Grace Healthcare Ltd | Public administration | 2023 |
| Spedding Dental Clinic Limited | Health & social care | 2007 |
| Spencer & Slade Estates Limited | Real estate | 2024 |
| Spencer Car Company (Carlisle) Limited | Transport & logistics | 1958 |
| Spencer Street Social Club Limited | Other services | 2024 |
| Spencer Street Surgery Limited | Health & social care | 2025 |
| SPG Broadcast Ltd | Information & communication | 2023 |
| Spinners Yard Management Limited | Households | 2009 |
| Spiritsweet Limited | Professional & scientific | 2001 |
| Spittal House Farm Limited | Agriculture & fishing | 2024 |
| Spj-Tamdee Ltd | Other services | 2026 |
| Spool Counselling Ltd. | Health & social care | 2025 |
| Sport in Action Ltd | Arts & recreation | 2013 |
| Spoutbank Farming Company Limited | Administrative & support | 2006 |
| SPR Cumbria Ltd | Transport & logistics | 2017 |
| Spring Field Management Company (Wetheral) Limited | Real estate | 2024 |
| Springfield Eco Limited | Construction | 2018 |
| SPS Northern Electricity Ltd | Energy | 2026 |
| Squashed Frog Music Limited | Information & communication | 2016 |
| SR Auto Shine Limited | Administrative & support | 2025 |
| SR Flavourz Hub Ltd | Hospitality | 2026 |
| SRC Motorsport Ltd | Arts & recreation | 2016 |
| SRE Associates (Cumbria) Limited | Professional & scientific | 2018 |
| SRJ Electrical Ltd | Manufacturing | 2023 |
| SRW Welding Limited | Manufacturing | 2022 |
| SSA Developments (Carlisle) Limited | Real estate | 1995 |
| ST Aidans Allotments Limited | Agriculture & fishing | 2013 |