| Sinova Pharma Limited | Professional & scientific | 2015 |
| Sintesya Limited | Information & communication | 2024 |
| Sioair Ltd | Manufacturing | 2024 |
| SIP & Snack Ltd | Wholesale & retail | 2024 |
| Siphnos Ltd | Information & communication | 2016 |
| Sips Studio LLP | | 2025 |
| SIR Property Improvements Ltd | Construction | 2022 |
| SIR Richard Olver Family Investment Company Limited | Financial services | 2020 |
| Sirbu 2026 Ltd | Manufacturing | 2026 |
| Sirbu Ionut Ltd | Manufacturing | 2024 |
| Sirf Limited | Extraterritorial | 2012 |
| Sirius Dynamics Ltd | Professional & scientific | 2024 |
| Sirius Marketing Ltd | Information & communication | 2023 |
| Sirius Quantum Solutions Ltd | Information & communication | 2021 |
| Sirovitaalex Ltd | Manufacturing | 2024 |
| Sisu Ventures Ltd | Information & communication | 2023 |
| Sitala BIO Ltd | Professional & scientific | 2021 |
| Sitase Ltd | Wholesale & retail | 2025 |
| Site Enhancements Limited | Construction | 2005 |
| Site Support Services Limited | Construction | 2021 |
| Site Web Developers Limited | Administrative & support | 2007 |
| Sitespeed Limited | Information & communication | 2002 |
| SIX Inches of Soil Ltd | Information & communication | 2021 |
| SIX Mile Bottom Shoot Ltd. | Arts & recreation | 2000 |
| SIX-1 Engineering Ltd | Professional & scientific | 2011 |
| Sixpoint Future International Ltd | Wholesale & retail | 2023 |
| Sixpoint International Trade Ltd | Wholesale & retail | 2024 |
| Sixpoint Investment Ltd | Wholesale & retail | 2023 |
| Sixx Precision Ltd | Manufacturing | 2016 |
| SJ and KS Ltd | Health & social care | 2016 |
| SJ Catling Ltd | Professional & scientific | 2014 |
| SJ Haggart Ltd | Professional & scientific | 2024 |
| SJ Performing Arts Limited | Arts & recreation | 2024 |
| SJ Property Letting & Management Ltd | Real estate | 2026 |
| SJ Psychological Services Limited | Health & social care | 2019 |
| SJA Mechanical Ltd | Construction | 2025 |
| SJB Electrical Contracting Limited | Construction | 2009 |
| SJB Machine Services Ltd | Manufacturing | 2022 |
| SJC Building Services (Cambridge) Ltd | Construction | 2000 |
| SJC CAM Limited | Financial services | 2025 |
| SJC MAY Ball Limited | Arts & recreation | 2023 |
| SJC Property Developments (Cambridge) Ltd | Real estate | 2019 |
| SJC Sourcing Limited | Real estate | 2022 |
| SJC Stannworks Ltd | Real estate | 2025 |
| SJC X MO Limited | Financial services | 2025 |
| Sjcl Investments Limited | Financial services | 2004 |
| Sjcs International Limited | Administrative & support | 2017 |
| SJH Advisory & Consulting Ltd | Professional & scientific | 2026 |
| SJK Property Investments Ltd | Real estate | 2018 |
| SJL Energy Services Limited | Manufacturing | 2026 |
| SJM Associates Limited | Administrative & support | 2024 |
| SJP Logistics Ltd | Administrative & support | 2026 |
| SJS Plumbing & Heating Limited | Construction | 2004 |
| SJS Tiling Ltd | Construction | 2014 |
| SJT Electrical Contractors (UK) Limited | Construction | 2013 |
| SK Modern Foods Ltd | Hospitality | 2019 |
| SKA Global Consultancy Ltd | Health & social care | 2022 |
| Skars Ltd | Wholesale & retail | 2016 |
| Skat Limited | Administrative & support | 2014 |
| Skat Training Academy Ltd | Education | 2020 |
| Skateboard Cambridge CIC | Education | 2022 |
| Skb-Structures Ltd | Construction | 2025 |
| SKD Aircraft Ltd | Manufacturing | 2026 |
| Skead Consulting Limited | Professional & scientific | 2020 |
| Skelding Hill Limited | Financial services | 2022 |
| Skerryvore AM LLP | | 2019 |
| Skerryvore Asset Management Ltd | Administrative & support | 2016 |
| Sketchbook Art Limited | Education | 2021 |
| Sketchline Designs Ltd | Professional & scientific | 2022 |
| Sketchpad Ltd | Real estate | 2025 |
| Skewer (Cambridge) Limited | Hospitality | 2019 |
| SKI Exchange (Holdings) Limited | Financial services | 2023 |
| SKI Exchange Brand Stores Ltd | Wholesale & retail | 2023 |
| SKI Exchange Limited(The) | Wholesale & retail | 1987 |
| Skill Express Private Ltd | Transport & logistics | 2020 |
| Skillsouq Ltd | Education | 2025 |
| Skilltime Limited | Information & communication | 2017 |
| Skin Analytics Ltd | Information & communication | 2012 |
| Skinandbliss.Com Limited | Wholesale & retail | 2012 |
| Skincare & More Ltd | Wholesale & retail | 2021 |
| Skinhealth UK Ltd | Health & social care | 2011 |
| Skinnbluoome Group Ltd | Wholesale & retail | 2026 |
| Skinny Kitten Events Ltd. | Administrative & support | 2011 |
| Skittrall Properties Limited | Real estate | 2020 |
| Skkgroup Ltd | Hospitality | 2020 |
| Skladusa Ltd | Wholesale & retail | 2022 |
| SKM Unique Consultancy Ltd | Information & communication | 2022 |
| SKM Unique Ltd | Real estate | 2018 |
| Skmn Ltd | Real estate | 2020 |
| SKN Stores Ltd | Wholesale & retail | 2024 |
| Skovlund Consulting Ltd | Professional & scientific | 2024 |
| Sktn Property Management Ltd | Real estate | 2025 |
| SKW Aviation Services Ltd | Transport & logistics | 2024 |
| Sky Blue Line 2025 Ltd | Administrative & support | 2025 |
| Sky Blue Line Ltd | Administrative & support | 2025 |
| Sky Chambers Manchester (UK) Ltd | Real estate | 2022 |
| Sky Wealth Chemical Co., Limited | Extraterritorial | 2016 |
| Sky Wold Trading Co., Limited | Wholesale & retail | 2023 |
| Skyeyecouch Ltd | Professional & scientific | 2026 |
| Skyfox Limited | Information & communication | 2024 |