| Synergised Consulting Ltd | Information & communication | 2012 |
| Synergy Global Alliance Foundation | Professional & scientific | 2018 |
| Synergy Health and Gender Limited | Health & social care | 2021 |
| Synergy Healthcare Solutions Limited | Health & social care | 2022 |
| Synergy Motors Ltd | Wholesale & retail | 2014 |
| Synergy Office (UK) Limited | Information & communication | 2004 |
| Synergy Office Solutions LLP | | 2010 |
| Synergy Office Technologies LLP | | 2014 |
| Synertek Ltd | Wholesale & retail | 2025 |
| Syon Coffee House Limited | Wholesale & retail | 2021 |
| Syon Financial Limited | Financial services | 2002 |
| SYP Confidence CIC | Administrative & support | 2021 |
| Sypat Limited | Education | 2013 |
| Syrj Homes Limited | Real estate | 2024 |
| Syrus Consultancy C.I.C. | Real estate | 2009 |
| Sysfix IT Support Ltd. | Information & communication | 2015 |
| Sysline Groups Ltd | Wholesale & retail | 2026 |
| System Plus Healthcare Services Ltd | Health & social care | 2014 |
| System Store Solutions Holdings Limited | Wholesale & retail | 2021 |
| Systomato Limited | Information & communication | 2014 |
| Syswood Fruits Limited | Wholesale & retail | 2013 |
| SZK London Limited | Hospitality | 2020 |
| SZY Ltd | Wholesale & retail | 2023 |
| SZZ Distributions Ltd | Wholesale & retail | 2026 |
| T & J Productions Ltd | Hospitality | 2017 |
| T & T Traders UK Limited | Wholesale & retail | 2026 |
| T a & Co Developments Ltd | Construction | 2019 |
| T a Best Plumbing Limited | Construction | 2019 |
| T a Best Properties Limited | Construction | 2025 |
| T and T Tech Ltd | Information & communication | 2013 |
| T James Pharma Limited | Wholesale & retail | 2025 |
| T Plumbing & Heating Limited | Wholesale & retail | 2002 |
| T Riley Development Limited | Construction | 2009 |
| T S a Drawing Limited | Hospitality | 2026 |
| T T Incorporate Limited | Real estate | 2008 |
| T Tutorial Limited | Education | 2020 |
| T&A IT Services Ltd | Information & communication | 2015 |
| T&B Construction Ltd | Construction | 2018 |
| T&D Beauty Limited | Real estate | 2012 |
| T&H Catering Ltd | Hospitality | 2022 |
| T&H Properties Northampton Ltd | Real estate | 2024 |
| T&J Stores Limited | Wholesale & retail | 2010 |
| T&L Holiday Ltd | Hospitality | 2023 |
| T&M Housing Ltd | Real estate | 2019 |
| T&M Shop Ltd | Wholesale & retail | 2022 |
| T&S Academy Ltd | Education | 2018 |
| T&T Party Solutions Ltd | Hospitality | 2025 |
| T-Link Solutions Limited | Information & communication | 2017 |
| T.D. Enterprises Limited | | 1980 |
| T.Diallo Elect Limited | Construction | 2022 |
| T.G. TM Limited | Transport & logistics | 2003 |
| T.Good & Sons Limited | Manufacturing | 1972 |
| T.Raychev-Building Services Limited | Construction | 2007 |
| T.S Bell Logistics Ltd | Transport & logistics | 2019 |
| T.V.Cartoons Limited | Information & communication | 1950 |
| T1A Ltd | Information & communication | 2017 |
| T2 Events Co. Ltd | Arts & recreation | 2025 |
| T2B Holding Limited | Financial services | 2023 |
| Taank (Derby) Limited | Wholesale & retail | 2005 |
| Tabin Business Ltd | Information & communication | 2024 |
| Tabitha's Foods Limited | Manufacturing | 2012 |
| Tachbrook Triangle Residents Management Company Limited | Households | 2005 |
| Tadorne (Tadworth) Management Company Limited | Households | 2015 |
| Tafii Childcare Services Ltd | Health & social care | 2019 |
| TAG Logistics Service Ltd | Transport & logistics | 2026 |
| Tagab Ltd | Wholesale & retail | 2026 |
| Tahn Ltd | Health & social care | 2022 |
| Taiho Contral System Co., Ltd | Wholesale & retail | 2025 |
| Tail ME Safely Ltd | Manufacturing | 2026 |
| TAILOR321 Limited | Wholesale & retail | 2020 |
| Tailored Time Limited | Professional & scientific | 2007 |
| Tailored Tuition London Limited | Education | 2019 |
| Tainted Arts London Limited | Wholesale & retail | 2018 |
| TAJ (2012) UK Ltd | Wholesale & retail | 2012 |
| TAJ Convenience Stores Ltd | Wholesale & retail | 2022 |
| TAJ Holdings (Croydon) Ltd | Real estate | 2025 |
| TAJ Holdings Limited | Construction | 2017 |
| Tajah Therapeutic Services Ltd | Health & social care | 2022 |
| Taka Marylebone Ltd | Hospitality | 2016 |
| Taka Mayfair Ltd | Hospitality | 2015 |
| Taka Tower Bridge Ltd | Hospitality | 2015 |
| Takedo International Consultants Limited | Professional & scientific | 1993 |
| Takelook Limited | Households | 1985 |
| TAL Umbrella Ltd | Administrative & support | 2017 |
| Tala Star and Moon Limited | Professional & scientific | 2025 |
| Talawa Theatre Company Limited | Arts & recreation | 1986 |
| Talent Shore Ltd | Other services | 2021 |
| Talentbase Entertainment Ltd | Education | 2022 |
| Tales of Inkspiration Limited | Other services | 2022 |
| Talk to the Hand Studios Limited | Arts & recreation | 2021 |
| Talk to Tich Ltd | Education | 2011 |
| TALK2EASYEE Logistics Ltd | Transport & logistics | 2022 |
| Talking IS Freedom Ltd | Health & social care | 2022 |
| Tall Tree Gardens Management Company Limited | Households | 2017 |
| Tallawah Events & Consultancy Limited | Education | 2023 |
| Tallawah Foods Limited | Manufacturing | 2026 |
| Tallijar CIC | Education | 2025 |
| Tally Medical Limited | Health & social care | 2018 |
| Tamar Burney Ltd | Other services | 2012 |
| Tamara Court Limited | Real estate | 2021 |