| NET Zero Tech Consulting Ltd | Extraterritorial | 2020 |
| NET Zero Tech Investments Ltd | Extraterritorial | 2020 |
| Neuralshift Limited | Information & communication | 2024 |
| New Aera Ltd | Manufacturing | 2017 |
| Newstyle Print Limited | Manufacturing | 2015 |
| Nexgen T&D Limited | Administrative & support | 2024 |
| Next ID Limited | Professional & scientific | 2018 |
| Next Steps Children's Care Ltd | Health & social care | 2026 |
| Nicholls Marketing Consultancy Limited | Professional & scientific | 2012 |
| Nick Parsons Ltd | Administrative & support | 2011 |
| Nick's Auto Repairs Limited | Wholesale & retail | 2016 |
| Nicolas Roberts Management Limited | Administrative & support | 2013 |
| Nigelgreen SCS Ltd | Professional & scientific | 2016 |
| Nimble Publishing Ltd | Information & communication | 2017 |
| Ninth Legion Studios Limited | Information & communication | 2025 |
| NL Global Ltd | Information & communication | 2013 |
| NO Time Ventures Limited | Professional & scientific | 1999 |
| Nomadical Chefs Limited | Hospitality | 2026 |
| Nomow International Limited | Construction | 2002 |
| Nomow Limited | Construction | 2001 |
| Nordic Walking Adventures Ltd | Education | 2023 |
| Normalec Limited | Wholesale & retail | 1949 |
| Normanton Park Hotel Limited | Hospitality | 2005 |
| North Cheshire Trading and Storage Limited | Agriculture & fishing | 1979 |
| Notorious Tattoo Oakham Limited | Other services | 2023 |
| Nottingham Building Systems Limited | Construction | 2013 |
| Novawave Ltd | Other services | 2018 |
| Npstreat Limited | Administrative & support | 2008 |
| NRS International PVT Limited | Administrative & support | 2010 |
| Nu-U Skin Ltd | Other services | 2021 |
| Nurture 4 Growth Limited | Professional & scientific | 2002 |
| NV Group Ltd | Wholesale & retail | 2018 |
| NVZ Advisers Ltd | Agriculture & fishing | 2008 |
| Nxtgen Technology Limited | Information & communication | 2014 |
| O&Ob Ltd | Administrative & support | 2023 |
| Oakham Automotive Ltd | Wholesale & retail | 2026 |
| Oakham Car Wash Limited | Administrative & support | 2020 |
| Oakham Fish Limited | Hospitality | 2022 |
| Oakham Galleries Limited | Wholesale & retail | 2020 |
| Oakham Garden Buildings Ltd | Construction | 2017 |
| Oakham Home Improvements Limited | Construction | 1990 |
| Oakham Minimart Ltd | Wholesale & retail | 2026 |
| Oakham Minishop Ltd | Wholesale & retail | 2025 |
| Oakham One Stop International Ltd | Wholesale & retail | 2026 |
| Oakham Retail Ltd | Wholesale & retail | 2023 |
| Oakham School | Education | 2009 |
| Oakham Self Storage Ltd | Real estate | 2017 |
| Oakham Stone Limited | Manufacturing | 2020 |
| Oakham Town Partnership Ltd | Administrative & support | 2012 |
| Oakham Tyre Co. (Rutland) Limited | Wholesale & retail | 1983 |
| Oakham United Football Club | Arts & recreation | 2012 |
| Oakham Wines Limited | Extraterritorial | 2010 |
| Obsessions Oakham Ltd | Wholesale & retail | 2022 |
| Occupational Therapy Consultants Limited | Administrative & support | 2011 |
| Oceanos Pools Limited | Construction | 2016 |
| Oddbod Games Studio Limited | Information & communication | 2014 |
| Odessia Holdings Ltd | Real estate | 2025 |
| Odom Electrical Limited | Construction | 2016 |
| Ogilvie & Wolfe Ltd | Information & communication | 2000 |
| Ohlogy Limited | Professional & scientific | 2016 |
| OHS Consultancy Ltd | Information & communication | 2020 |
| OIL and Gasoline Ltd | Wholesale & retail | 2018 |
| Okham New Hotel Limited | Hospitality | 2025 |
| Old Hall Farm (Cottesmore) Limited | Real estate | 2012 |
| Old Manor Artisans Limited | Manufacturing | 2019 |
| Omnilux Lighting Limited | Manufacturing | 2023 |
| Onai Shamiso Limited | Health & social care | 2025 |
| One Stop Tech Shop Limited | Information & communication | 2011 |
| Opalite Events Ltd | Administrative & support | 2025 |
| Operational Expertise Limited | Professional & scientific | 2022 |
| Opna Investments Limited | Extraterritorial | 2023 |
| Opportunity Chalet - Rutland and Melton | Hospitality | 2011 |
| Optimal One Consultancy Limited | Professional & scientific | 2016 |
| Orbis Stamford 2021 Ltd | Hospitality | 2022 |
| Orchid at Oakham Management Company Limited | Households | 2011 |
| Organic.Ritual.Beauty Limited | Manufacturing | 2021 |
| Osprey Electrical Contractors Ltd | Construction | 2022 |
| Osprey Helm Ltd | Real estate | 2022 |
| Otters Smokehouse and Deli Ltd | Wholesale & retail | 2011 |
| Ottih Properties Ltd | Real estate | 2026 |
| Outsourcing and Procurement Consultants Limited | Professional & scientific | 2012 |
| Ovation Bar Services Ltd | Hospitality | 2025 |
| Owen & Partners Ltd | Professional & scientific | 2020 |
| Owlk Limited | Professional & scientific | 2015 |
| P & M Amusements Limited | Arts & recreation | 2005 |
| P J Plumbing & Heating Ltd | Construction | 2003 |
| P Mcgeough & Sons Limited | Arts & recreation | 2026 |
| P R Burdett Fencing Limited | Agriculture & fishing | 2007 |
| P-J W H (SPV) Limited | Real estate | 2018 |
| P-J W H Associates Limited | Real estate | 2007 |
| Pacesetter Events Ltd | Arts & recreation | 2014 |
| Pacwolf Fulfilment Limited | Professional & scientific | 1979 |
| Pacy Care Group Ltd | Health & social care | 2021 |
| Padel Sixty-Four Ltd | Arts & recreation | 2025 |
| Page by Paige Accountancy Ltd | Professional & scientific | 2024 |
| Paint IT OR Plant IT (Rutland) Limited | Construction | 2005 |
| Panacea Cottages Limited | Real estate | 2024 |
| Panacea PM Ltd | Real estate | 2013 |
| Panchamp Ltd | Wholesale & retail | 2020 |
| Paper Plane Designs Ltd | Wholesale & retail | 2017 |