| Revegate Aberystwyth Ltd | Other services | 1986 |
| Rheidol Developments Ltd. | Real estate | 1998 |
| Rhian Ltd | Transport & logistics | 2024 |
| Rhodri Jenkins Limited | Construction | 2013 |
| Richard D Pugh & Sons | | 2003 |
| Ride Free Ltd | Administrative & support | 2022 |
| Right Price Carpets Aberystwyth Ltd | Wholesale & retail | 2018 |
| Rise UP Group Ltd | Construction | 2023 |
| Rizquha Care Ltd | Health & social care | 2026 |
| RND Real Estate Ltd | Real estate | 2024 |
| Roberts Plumbing Ltd | Construction | 2026 |
| Robinhood.Network Ltd | Information & communication | 2020 |
| Rogues Coffee Ltd | Manufacturing | 2021 |
| Roof-Master UK Limited | Wholesale & retail | 2005 |
| Rosehill Flat Management (Aberystwyth) Limited | Households | 1986 |
| RTT Environmental Consultancy Services Ltd | Professional & scientific | 2026 |
| RWJ Hire Limited | Construction | 2013 |
| Ryan Rickard Electrical Ltd | Construction | 2021 |
| S Vaughan & Sons Limited | Real estate | 2022 |
| S&L Plumbing and Heating Ltd | Construction | 2021 |
| S&M Global Ventures Limited | Administrative & support | 2026 |
| S.P.S Carpentry & Building Ltd | Construction | 2013 |
| S.R.M. Engineering Limited | Manufacturing | 1998 |
| Safenetuk Ltd | Construction | 2020 |
| Safetynet Systems Ltd | Information & communication | 1997 |
| Salken Ltd | Administrative & support | 2022 |
| SAM Symons Stunts Ltd | Arts & recreation | 2022 |
| Samakara Ltd | Construction | 2026 |
| Saman Abid Global Corporation Limited | Information & communication | 2024 |
| Sanarchana Care Company Limited | Health & social care | 2020 |
| Saphan at the Black Ltd | Hospitality | 2023 |
| Sarah Bunton Chocolate Ltd | Manufacturing | 2023 |
| Sea Escapes Ltd | Hospitality | 2023 |
| Seema Tech Limited | Information & communication | 2026 |
| Seidr Pisgah CHI CYF | Manufacturing | 2020 |
| Seikel Ltd | Wholesale & retail | 2018 |
| Selectfor Limited | Agriculture & fishing | 2000 |
| Seren Bell Ltd | Wholesale & retail | 2023 |
| Sgema CYF | Professional & scientific | 2004 |
| Shear Property Ltd | Hospitality | 2017 |
| Shire Meadery Ltd. | Manufacturing | 2018 |
| Shirwell Avenue Ltd | Professional & scientific | 2024 |
| Shon Morris Plumbing & Heating Engineers Limited | Construction | 2010 |
| Silage Solutions Ltd | Agriculture & fishing | 2010 |
| Silver Fern Glamping Ltd | Hospitality | 2022 |
| Silver Mine Attractions Limited | Arts & recreation | 2003 |
| Silver River Mines Limited | Real estate | 1995 |
| Silverback Exterior Cleaning Limited | Administrative & support | 2018 |
| Sioned Properties Ltd | Real estate | 2023 |
| Siop Ffoto Shop Limited | Professional & scientific | 2013 |
| Siop Inc CYF | Wholesale & retail | 2026 |
| Siop Y Cymro Ltd | Wholesale & retail | 2025 |
| Siop Y Pethe CYF | Wholesale & retail | 2015 |
| Skindeep Calon Cymru Ltd | Other services | 2018 |
| Sky Delta Ltd | Financial services | 2025 |
| Sky Solidarity CIC | Administrative & support | 2025 |
| Skynas Limited | Hospitality | 2019 |
| Smartdata UK Limited | Information & communication | 2000 |
| Solutions Chemical Ltd | Administrative & support | 2016 |
| Solutionvault Technologies Ltd | Information & communication | 2025 |
| Sonny Vaughan Electrical Ltd. | Construction | 2018 |
| South West Wales Homes Ltd | Extraterritorial | 2016 |
| Specere Limited | Information & communication | 2014 |
| Spencer Thomas Property Limited | Real estate | 2025 |
| Spiral Plumbing and Heating Limited | Construction | 2016 |
| Spork Studios Ltd | Manufacturing | 2024 |
| Square Prints Ltd | Manufacturing | 2022 |
| ST David's Snooker Club Limited | Arts & recreation | 2017 |
| ST Michael's Car Park Limited | Real estate | 2010 |
| ST. Aaron Limited | Health & social care | 2015 |
| ST. David's Quay Management Company Limited | Households | 1996 |
| Star Family Holdings Ltd | Financial services | 2024 |
| Star Family Investments Ltd | Financial services | 2024 |
| Starfish Labs Limited | Information & communication | 2019 |
| Starlight IT Ltd | Information & communication | 2023 |
| Stencraft Limited | Manufacturing | 2013 |
| Stephen Cham Mortgage and Financial Services Ltd | Financial services | 2015 |
| Stephens Property Development Ltd | Real estate | 2019 |
| Sterling (Aberystwyth) Limited | Real estate | 2014 |
| Sterling Asset Management Ltd | Professional & scientific | 2013 |
| Steve Davies Glaziers Ltd | Construction | 2025 |
| Stiwdio Fforest Ltd | Information & communication | 2024 |
| Stonewick Studio Ltd | Manufacturing | 2025 |
| STR Roofing & Solar CYF | Construction | 2026 |
| Studt Limited | Wholesale & retail | 2005 |
| Sugars for Health Limited | Professional & scientific | 2014 |
| Summit Cycles Ltd | Wholesale & retail | 2014 |
| Sunlabob Renewable Energy Ltd | Professional & scientific | 2019 |
| Sunnycroft Management Company Ltd | Households | 2018 |
| Superior Finish Decorating (Wales) Ltd | Construction | 2021 |
| Supertrooper Ltd | Hospitality | 2014 |
| Susanol Services Limited | Health & social care | 2023 |
| Sushi Sensations Limited | Hospitality | 2024 |
| Sustainable Forest Management Limited | Agriculture & fishing | 1998 |
| Swanson's Conversions Ltd | Manufacturing | 2026 |
| Swimstart Swimschools Training Consultancy Limited | Arts & recreation | 2006 |
| Swindells Group Ltd | Financial services | 2019 |
| Swindells Music Ltd | Administrative & support | 2017 |
| Swopme Ltd | Wholesale & retail | 2018 |
| SY23 Ltd | Wholesale & retail | 2014 |