| Swiss Physio Limited | Health & social care | 2009 |
| Switch Business GAS and Power Ltd | Information & communication | 2020 |
| Switch GAS and Electric Limited | Professional & scientific | 2022 |
| Switch GAS and Electric Online Limited | Professional & scientific | 2015 |
| Switch UK Online Ltd | Administrative & support | 2011 |
| Switchwin Limited | Households | 1989 |
| Swka Services Ltd | Professional & scientific | 2014 |
| SWL (Teesside) Ltd | Construction | 2023 |
| Swpm Consulting Ltd | Professional & scientific | 2026 |
| SWS Logistics (NE) Ltd | Transport & logistics | 2026 |
| Swtb Holdings Limited | Information & communication | 2026 |
| Syara Health Ltd | Wholesale & retail | 2025 |
| SYC Carbon Limited | Wholesale & retail | 2025 |
| Sycamore Design Ltd | Professional & scientific | 2026 |
| Sycamore Emea Ltd | Information & communication | 2025 |
| Sycamore Grove (Walkergate) Management Company Limited | Households | 2022 |
| Sycamore Growth Partners Ltd | Wholesale & retail | 2026 |
| Sycamore NET Zero Community Interest Company | Professional & scientific | 2023 |
| Sycamore Square Management Co Limited | Households | 2021 |
| SYD Hewett Limited | Construction | 1974 |
| Sydneygrovesolutions Ltd | Professional & scientific | 2024 |
| Syed’S and Sons Ltd | Wholesale & retail | 2026 |
| Sylhet Cash & Carry Express Ltd | Wholesale & retail | 2026 |
| Sylhet Cash & Carry Limited | Wholesale & retail | 2011 |
| Sylhet Spice-Southshields Ltd | Hospitality | 2025 |
| Sylvester Properties Ltd | Real estate | 2014 |
| Sylyve Home Care Limited | Health & social care | 2023 |
| SYM Property Limited | Construction | 2014 |
| Symco Developments Limited | Construction | 2007 |
| Symonds Taylor Limited | Real estate | 2023 |
| Sympraxis Consulting Ltd | Education | 2026 |
| Syncopated Rhythm Ltd | Arts & recreation | 2015 |
| Synergi Search Limited | Administrative & support | 2020 |
| Synergy GAS and Property Services Ltd | Other services | 2018 |
| Syntax Holdings Limited | Financial services | 2026 |
| Synthara Research Ltd | Wholesale & retail | 2026 |
| Syon Leisure (NE) Ltd | Hospitality | 2021 |
| Syrona Limited | Manufacturing | 2018 |
| Sysaro Systems Limited | Information & communication | 2009 |
| System Consulting Ltd | Professional & scientific | 2023 |
| Syze UK Ltd | Wholesale & retail | 2013 |
| SZ Homes Ltd | Real estate | 2021 |
| S’Y IT Ltd | Information & communication | 2025 |
| T & a Realty Limited | Real estate | 2024 |
| T & E Healthcare Ltd | Administrative & support | 2017 |
| T & T Business Solutions Ltd | Professional & scientific | 2024 |
| T D Cleaning & Maintenance Limited | Households | 2018 |
| T English Opticians Ltd | Wholesale & retail | 2022 |
| T G Paving Specialists Limited | Construction | 2013 |
| T Green Consulting Limited | Professional & scientific | 2022 |
| T H Adamson Limited | Administrative & support | 2007 |
| T J Makers Ltd | Manufacturing | 2022 |
| T LEE 88 Ltd | Hospitality | 2014 |
| T M a Property Consultants Limited | Professional & scientific | 2008 |
| T Neary Ltd | Construction | 2018 |
| T P Clarke Groundworks Limited | Other services | 1994 |
| T Pattinson Plumbing & Heating Ltd | Construction | 2026 |
| T R Dixon & Co Ltd | Professional & scientific | 2014 |
| T R Mitchell Consultancy Ltd | Real estate | 2024 |
| T S Lowther Ltd | Transport & logistics | 2024 |
| T&N Limited | Real estate | 2018 |
| T&S Business Ltd | Real estate | 2022 |
| T&S UK Enterprise Limited | Professional & scientific | 2024 |
| T&T Building Solutions Ltd | Construction | 2026 |
| T-Mak Healthcare Ltd | Health & social care | 2024 |
| T-Services (N.E.) Limited | Administrative & support | 2010 |
| T. Leisure Limited | Hospitality | 2002 |
| T.Dawson & Co.Limited | Extraterritorial | 1960 |
| T.E.Liddell Limited | Wholesale & retail | 1957 |
| T.I.Woods Cake Designs Ltd | Manufacturing | 2025 |
| T.M.P. Mobile Motor Parts Limited | Wholesale & retail | 2008 |
| T.R. Interiors Limited | Construction | 2011 |
| T.T.Walker(Newcastle)Limited | Agriculture & fishing | 1952 |
| T2 Brilliance Ltd | Real estate | 2026 |
| T23 Ltd | Construction | 2023 |
| T24 Logistics Ltd | Transport & logistics | 2026 |
| T2O Engineers Ltd | Professional & scientific | 2013 |
| T3 Security Limited | Administrative & support | 2012 |
| T4 Building Services Limited | Construction | 2015 |
| T6 Marine Ltd | Manufacturing | 2024 |
| TA Domestic Ltd | Construction | 2026 |
| TA Gardening Limited | Administrative & support | 2024 |
| TA Sales and Marketing Ltd | Wholesale & retail | 2018 |
| Ta-Ha Consultancy Ltd | Professional & scientific | 2021 |
| Tabitha 365 Community Interest Company | Health & social care | 2023 |
| Tabriz Foods Limited | Hospitality | 2017 |
| TAC Group Holdings Ltd | Administrative & support | 2018 |
| TAC Operations Ltd | Administrative & support | 2018 |
| Tacit Security Services Limited | Administrative & support | 2023 |
| Tada Websites Limited | Information & communication | 2025 |
| Tadoc Investments Limited | Real estate | 2018 |
| Tads Business and Trading Ltd | Wholesale & retail | 2025 |
| TAF Service Solution Ltd | Information & communication | 2017 |
| TAG Sports CIC | Arts & recreation | 2023 |
| Tagetes Enterprises Limited | Real estate | 2022 |
| Tagetes Limited | Health & social care | 2023 |
| Tahera Sultana Ltd | Other services | 2019 |
| Tahir Property Ltd | Real estate | 2024 |
| Tahke Monite Limited | Financial services | 2016 |
| TAI Lung Fung Ltd | Wholesale & retail | 2024 |