| Metal (Holdings) Trustees Limited | Professional & scientific | 2024 |
| Metalcraft Cornwall Ltd | Manufacturing | 2010 |
| Metaphysical Developments Ltd | Information & communication | 2023 |
| Metre Yacht Restorations Limited | Manufacturing | 2018 |
| Meudon Farm Limited | Agriculture & fishing | 2005 |
| Miami's Food & Drinks Limited | Hospitality | 2022 |
| MIC Capital Ltd | Financial services | 2019 |
| MID Cornwall Printing Limited | Manufacturing | 2022 |
| Mid-Cornwall Roofing Contractors Limited | Construction | 1982 |
| Millennium Management (Penryn 2006) Limited | Real estate | 2006 |
| Milton Land Partners Limited | Real estate | 2021 |
| Mindfulness Cornwall C.I.C. | Health & social care | 2011 |
| Miracle Theatre Productions Ltd | Arts & recreation | 2016 |
| Miracle Theatre Trust Limited | Arts & recreation | 1986 |
| MJM Flooring Ltd | Wholesale & retail | 2016 |
| Mobility Hire Limited | Administrative & support | 2011 |
| Mobility Warehouse Limited | Extraterritorial | 2010 |
| Money Debt and Credit Limited | Financial services | 2005 |
| Mono Construction Ltd | Construction | 2004 |
| Moogie Wonderland Ltd | Arts & recreation | 2009 |
| Moonshine Studios Ltd | Information & communication | 2018 |
| MOR Architecture Ltd | Professional & scientific | 2025 |
| MOR Clinic Ltd | Health & social care | 2022 |
| MOR Investments LLP | | 2015 |
| More Systems Limited | Information & communication | 2009 |
| Morgan and Bradbury Company Limited | Construction | 2004 |
| Mortimer Construction Limited | Construction | 2018 |
| Mosaic SW Ltd | Administrative & support | 2020 |
| MOY Design Limited | Arts & recreation | 2018 |
| Mozley Consultancy Services Ltd | Manufacturing | 2025 |
| MR B'S Ice Cream (Cornwall) Limited | Wholesale & retail | 2016 |
| MSH Plumbing and Heating SW Ltd | Construction | 2025 |
| Mulberry Court Management Company (Falmouth) Limited | Households | 1985 |
| Mulberry Quay Management Company Limited | Households | 1985 |
| Mycard.Earth Limited | Administrative & support | 2020 |
| Mylor Mooring Services Limited | Transport & logistics | 2017 |
| Myroxlab Ltd | Wholesale & retail | 2025 |
| Mysafe Limited | Information & communication | 2024 |
| Naku Studio Ltd | Arts & recreation | 2025 |
| Nampara Court Management Company Limited | Households | 1985 |
| NAS Marine Consultancy Ltd | Professional & scientific | 2026 |
| National Charging Solutions Ltd | Construction | 2026 |
| National Mobility Limited | Extraterritorial | 2016 |
| NB73 Limited | Arts & recreation | 2019 |
| NCC Retail Ltd | Wholesale & retail | 2012 |
| New Foundation Farms Ltd | Agriculture & fishing | 2018 |
| New Vision Online Ltd | Wholesale & retail | 2017 |
| Nick Ferris Skip Hire Limited | Water & waste | 2001 |
| Nield Ltd | Financial services | 2020 |
| Ninja Nyan Ltd | Manufacturing | 2019 |
| Nixon Design Limited | Administrative & support | 2003 |
| NO One Dies Alone Cornwall C.I.C. | Health & social care | 2023 |
| NO.1 Cubs Ltd | Wholesale & retail | 2018 |
| Noah's ARK Footcare Limited | Health & social care | 2013 |
| NORTH55CORNWALL Ltd | Wholesale & retail | 2021 |
| NTK Developments (SPV3) Ltd | Construction | 2020 |
| NTK Developments Ltd | Construction | 2019 |
| Nuhaus Ltd | Real estate | 2020 |
| Numerous Holding Limited | Financial services | 2020 |
| O&O Management Limited | Professional & scientific | 2014 |
| O.W.E. Developments Limited | Construction | 2012 |
| Oakville Resources Limited | Administrative & support | 2014 |
| Obrien Building Ltd | Construction | 2005 |
| Obriens Construction Ltd | Construction | 2018 |
| OC Hydrographic Services Limited | Professional & scientific | 2016 |
| OFF Road Mobility Limited | Administrative & support | 2022 |
| OFF the Beaten Track Glamping Ltd | Hospitality | 2025 |
| OH SO Savvy Limited | Information & communication | 2018 |
| OKE Computer Repairs Limited | Information & communication | 2024 |
| OLA Crown Limited | Construction | 2025 |
| Olfactory Coffee Ltd. | Manufacturing | 2013 |
| Olfactory Coffee Shop Limited | Hospitality | 2024 |
| Olju Lodges Ltd | Hospitality | 2021 |
| Optimal Health Group Limited | Health & social care | 2022 |
| Opus Carpentry and Interiors Ltd | Construction | 2017 |
| Oral Rehab LAB Ltd | Health & social care | 2021 |
| Oram Enterprises Ltd | Wholesale & retail | 2022 |
| Oranges for Sharing CIC | Education | 2024 |
| Orca Marine Coatings Ltd | Manufacturing | 2021 |
| Orchard House (RS) Management Company Limited | Real estate | 2021 |
| Oriental Horizon Limited | Wholesale & retail | 2004 |
| Ospray Bespoke Joinery Limited | Manufacturing | 2001 |
| Osprey Health and Safety Services Ltd | Professional & scientific | 2021 |
| Outdoor Shading Cornwall Ltd | Construction | 2024 |
| Outreachable Ltd | Information & communication | 2023 |
| Outside View Designs Ltd | Professional & scientific | 2025 |
| Oystercatcher Property Limited | Real estate | 2024 |
| P & C Upholstery Limited | Manufacturing | 2003 |
| P Jeffery Painters and Decorators Ltd | Construction | 2021 |
| P&S Seaware Limited | Professional & scientific | 2014 |
| Packet Quays Management Limited | Households | 1985 |
| Packet Ship Technologies Limited | Information & communication | 2005 |
| PAD Design Limited | Professional & scientific | 2007 |
| Padel Tide Ltd | Arts & recreation | 2025 |
| Palas Ltd | Construction | 2019 |
| PAM Education Consultancy Services Limited | Education | 2016 |
| Pantscancers | Health & social care | 2011 |
| Paragon Electronics Clocks and Assembly Limited | Manufacturing | 2002 |
| Park Villa Management Limited | Households | 2008 |
| Parnies Limited | Transport & logistics | 2015 |