| Seaside Cinema Society CIC | Arts & recreation | 2025 |
| Seaside Leisure UK Limited | Wholesale & retail | 2018 |
| Seaside Pizza & Kebab Ltd | Hospitality | 2021 |
| Seaview Self Catering Ltd | Hospitality | 2026 |
| Seaviews Weymouth Ltd | Hospitality | 2020 |
| Seaward Travel Limited | Transport & logistics | 2003 |
| Seconds OUT Boxing Limited | Arts & recreation | 2018 |
| Secure Storage South West Limited | Transport & logistics | 2017 |
| Sedgemoor Care Home Ltd | Real estate | 2025 |
| Seedfield HR Solutions Ltd | Administrative & support | 2020 |
| Select Portfolio Limited | Real estate | 2021 |
| Self Lettings Limited | Real estate | 2023 |
| Selves Investments Limited | Professional & scientific | 1999 |
| Selves Property Investments Limited | Real estate | 1999 |
| Sema Caterers Limited | Hospitality | 1998 |
| Serenity Care Circle Limited | Health & social care | 2021 |
| Serenus Locus Ltd | Real estate | 2023 |
| Servitas Organisation (UK) Limited | Administrative & support | 2012 |
| Servitas Property Services Ltd | Administrative & support | 2014 |
| Sevamor Associates Limited | Professional & scientific | 2010 |
| Sevensioux Limited | Information & communication | 2001 |
| Sevenstone Advisory Ltd. | Administrative & support | 2023 |
| Seventh Wave Production Group Limited | Administrative & support | 2026 |
| Sexybliss Limited | Information & communication | 2005 |
| SF Electrical and Alarm Systems Limited | Construction | 2010 |
| Shanenash Plumbing Ltd Ltd | Construction | 2025 |
| Shark Cars Ltd | Transport & logistics | 2024 |
| Shark Security Services Ltd | Administrative & support | 2024 |
| Sharkys FUN Factory Limited | Arts & recreation | 2015 |
| Sharpe Carpentry Limited | Manufacturing | 2020 |
| Sharpshore Limited | Financial services | 2003 |
| Shaun Milligan Building and Civil Engineering Services Ltd | Construction | 2016 |
| Shaun Williams Carpentry LLP | | 2011 |
| Sheikh Property Dorset Limited | Real estate | 2023 |
| Shelleys Bakery Limited | Wholesale & retail | 2001 |
| Shepherd Court Residents Ltd | Real estate | 2002 |
| Sheppard Holdings (U.K) Limited | Financial services | 2018 |
| Sheppard Investments (U.K) Limited | Financial services | 2018 |
| Sheppard Piling Limited | Construction | 2014 |
| Sheppard Plant & Property Limited | Administrative & support | 2018 |
| Sherpa Scientific Ltd | Information & communication | 2020 |
| SHM Management (Weymouth) Limited | Real estate | 1998 |
| Shoescape Consulting Limited | Professional & scientific | 2020 |
| Shoreline MEP Ltd | Professional & scientific | 2025 |
| Shoreline Productions Ltd | Administrative & support | 2019 |
| Short GIG Ltd | Information & communication | 2025 |
| Shotline Charters Limited | Education | 2003 |
| Show Site Services Limited | Water & waste | 2000 |
| Siaes Limited | Construction | 2023 |
| Side by Side Training Limited | Education | 2024 |
| Sidflo Limited | Real estate | 2001 |
| Silenpro Ltd | Wholesale & retail | 2023 |
| Silklake Management Co Ltd | Households | 2020 |
| Silly Soxx Limited | Wholesale & retail | 2021 |
| Simcoaccommodations Ltd | Real estate | 2026 |
| Simeon Stewart Limited | Construction | 2003 |
| Simon Smith Sports & Talent Ltd | Professional & scientific | 2014 |
| Simple Solutions (Weymouth) Ltd | Manufacturing | 2010 |
| Simply Brilliant Stuff Ltd | Wholesale & retail | 2012 |
| Simply SRS Limited | Administrative & support | 2007 |
| Sirius Business Centre Ltd | Administrative & support | 2011 |
| Sirius Business Services Ltd. | Education | 2000 |
| Sirius Property Services Ltd | Real estate | 2020 |
| Site Right Surveyors Ltd | Professional & scientific | 2012 |
| SJ Podiatry Ltd | Health & social care | 2014 |
| SJH Fibreglass Flat Roofing Limited | Construction | 2016 |
| SJM Services Dorset Ltd | Construction | 2023 |
| SK Collob Investments Ltd | Real estate | 2023 |
| Skelly Construction Ltd | Construction | 2011 |
| SKI Morzine Limited | Administrative & support | 2000 |
| Skidmarx UK Limited | Manufacturing | 1999 |
| Skills Ability Weymouth Limited | Hospitality | 2026 |
| Skin Deeper (Weymouth) Ltd | Transport & logistics | 2015 |
| Skye's House Limited | Real estate | 2025 |
| Skynet 800 Limited | Financial services | 2023 |
| Skyplex Holding Limited | Financial services | 2024 |
| Skyplex Properties Limited | Real estate | 1999 |
| SL Training and Development Limited | Education | 2022 |
| Sladesproperty Limited | Real estate | 2026 |
| Slip Limited | Wholesale & retail | 2017 |
| Smark Solutions Ltd | Information & communication | 2018 |
| Smart Clickers Limited | Wholesale & retail | 2025 |
| Smart Lock Solutions Limited | Construction | 2015 |
| Smart Move Developments Ltd | Administrative & support | 2008 |
| Smart Stores PVT Ltd | Wholesale & retail | 2018 |
| Smarteq Ltd | Information & communication | 2024 |
| Smarter-Eco Ltd | Construction | 2021 |
| Smashed IT Games Ltd | Wholesale & retail | 2025 |
| SMB Design & Consultancy Ltd | Professional & scientific | 2014 |
| SMM Composites Ltd | Administrative & support | 2016 |
| Snbenn Ltd | Hospitality | 2018 |
| Sndor Ltd | Hospitality | 2022 |
| Snell Mitchell & Co. Ltd. | Wholesale & retail | 2013 |
| Snipegate Dog Boarding Limited | Agriculture & fishing | 2023 |
| Snipegate Lettings Limited | Real estate | 2024 |
| Snoe Ltd | Wholesale & retail | 2017 |
| Snookes Sports Bar Limited | Arts & recreation | 2015 |
| SNS Catering Weymouth Limited | Hospitality | 2013 |
| SNS Property Limited | Real estate | 2014 |
| SO N Sews Ltd | Wholesale & retail | 2018 |