| TIER1 Gaming Ltd | Arts & recreation | 2024 |
| Tiger Medical Limited | Administrative & support | 2011 |
| Tiger WAX and Waves Limited | Administrative & support | 2024 |
| Tigerra Limited | Financial services | 2025 |
| Tight Lines Community Interest Company | Agriculture & fishing | 2022 |
| TIM Cockerill Ltd | Information & communication | 2023 |
| TIM Manhire Agricultural Consultancy Limited | Professional & scientific | 2010 |
| Timberwolf Developments Ltd | Construction | 2024 |
| Time & Tide Financial Planning Ltd | Financial services | 2025 |
| Timeless Group Limited | Construction | 2024 |
| TIN Cloud Ltd | Information & communication | 2019 |
| Tippetts Place Management Company Limited | Households | 2017 |
| Tiramisugo Ltd | Manufacturing | 2018 |
| Tissymin Ltd | Real estate | 2025 |
| Titans Basketball Club Cornwall CIC | Education | 2023 |
| Titman Electrical Ltd | Construction | 2024 |
| Tj's Accessories Ltd. | Wholesale & retail | 2020 |
| TJA Property Solutions LLP | | 2023 |
| TJR FIC Limited | Financial services | 2018 |
| TKN Aktivum Ltd. | Extraterritorial | 2008 |
| TKZ Gill Foods Ltd | Wholesale & retail | 2025 |
| TL Inventories Ltd | Professional & scientific | 2021 |
| TLG Lbtn Ltd | Professional & scientific | 2022 |
| TMJ Massage Therapies Ltd | Wholesale & retail | 2026 |
| Tnfp Taxis Ltd | Transport & logistics | 2011 |
| Tocardo Limited | Extraterritorial | 2020 |
| Together Digital Ltd | Information & communication | 2018 |
| Tolcarne Management Company | Real estate | 2016 |
| Tolcarne Project Limited | Construction | 2015 |
| Toldish Group Ltd | Agriculture & fishing | 2020 |
| Toliman Developments Ltd | Construction | 2014 |
| Tolvern Property Ltd | Real estate | 2025 |
| Tommo Ltd | Information & communication | 2024 |
| Tonks Family Ltd | Financial services | 2023 |
| Tony Button Consultancy Ltd | Wholesale & retail | 2013 |
| Tony Oates Garage Limited | Wholesale & retail | 2024 |
| Topgun Autos Ltd | Wholesale & retail | 2025 |
| TOR Mark Limited | Information & communication | 2019 |
| Tors Reach Limited | Households | 2009 |
| Tosi Limited | Professional & scientific | 2011 |
| Total Health Cornwall Limited | Health & social care | 2009 |
| Totally Truro | Professional & scientific | 2007 |
| Tower House (Lostwithiel) Management Company Limited | Real estate | 1997 |
| Toybox Agency Limited | Professional & scientific | 2003 |
| Toybox Nanny Agency Limited | Professional & scientific | 2003 |
| TPA Leisure Limited | Hospitality | 2015 |
| TR1 Storage Limited | Transport & logistics | 2019 |
| TR14ERS Community Dance Charity Limited | Arts & recreation | 2009 |
| TR2 Building & Electrical Services Ltd | Extraterritorial | 2015 |
| TR2 Recruitment Ltd | Professional & scientific | 2021 |
| Tradecycle Limited | Information & communication | 2026 |
| Tradesave+ Limited | Information & communication | 2026 |
| Trail Munki Ltd | Wholesale & retail | 2016 |
| Training in Action Consulting Limited | Financial services | 2016 |
| Tramways Limited | Health & social care | 2018 |
| Transatlantic Photography Film and Games Ltd | Information & communication | 2022 |
| Transform Construction (Cornwall) Limited | Construction | 2018 |
| Transformation Cornwall | Health & social care | 2010 |
| Transformer Electrical Ltd | Construction | 2024 |
| Transposition Architects Limited | Professional & scientific | 2002 |
| Travaux Sauvages Limited | Arts & recreation | 2007 |
| Travel Go Taxis Ltd | Transport & logistics | 2026 |
| Travel With a Paddle Ltd | Administrative & support | 2023 |
| Treadwell Pro Ltd | Wholesale & retail | 2025 |
| Treago & Trebellan Ltd | Hospitality | 2026 |
| Treanmor Ltd | Manufacturing | 2026 |
| Trearren Management Company Limited | Households | 2007 |
| Trebarwith Court Management Company Limited | Households | 1997 |
| Tredrea Manor Hotel Limited | | 1963 |
| Treehouse Apartments (Falmouth) Management Company Limited | Real estate | 2024 |
| Treen's Brewery Ltd. | Manufacturing | 2016 |
| Tregassow Farming Operations Limited | Agriculture & fishing | 1971 |
| Tregea Parc (NO 2) Management Company Limited | Households | 2015 |
| Tregea Parc Management Company Limited | Households | 2012 |
| Tregellans Properties Ltd | Real estate | 2022 |
| Tregenna LEA Management Company Limited | Households | 2021 |
| Tregidden Orchard CIC | Agriculture & fishing | 2025 |
| Tregiffian Holdings Ltd | Financial services | 2022 |
| Tregloweth Truro Management Company Limited | Households | 2009 |
| Treglyn Holiday Cottages Limited | Households | 2003 |
| Tregolls (Truro) Management Company Limited | Households | 2006 |
| Tregolls Manor Homes Limited | Health & social care | 1992 |
| Tregolls Parc (Plots 501 and 502) Management Company Limited | Households | 2011 |
| Tregongeeves Limited | Administrative & support | 2007 |
| Tregraph Properties Limited | Real estate | 1998 |
| Tregundy Court Limited | Households | 1972 |
| Tregurtha Wind Limited | Energy | 2013 |
| Treharrock Foliar Feeds Limited | Agriculture & fishing | 2006 |
| Trelander and ST Clements Community Association | Other services | 2008 |
| Trelawney Builders Limited | Construction | 2018 |
| Trelawney Fish Ltd | Wholesale & retail | 2022 |
| Trelawney Limited | Construction | 1987 |
| Trelawney Pools & Leisure Limited | Construction | 2004 |
| Trelean Barns (Cornwall) Management Company Limited | Households | 2013 |
| Treleaven Capital Limited | Real estate | 2026 |
| Treleaven Countryside Services Limited | Agriculture & fishing | 2019 |
| Treleaven Developments Limited | Real estate | 2006 |
| Treliske Airway Day Community Interest Company | Health & social care | 2025 |
| Treliske Estates Limited | Real estate | 1936 |
| Treloan Campsite Limited | Hospitality | 2023 |