| My Home Shop Ltd | Wholesale & retail | 2022 |
| My.Lab Stamford Rentals Ltd | Real estate | 2025 |
| MY04 Consultants Limited | Professional & scientific | 2022 |
| Myers Law Ltd | Professional & scientific | 2026 |
| Mygc Limited | Professional & scientific | 2022 |
| Mygratuity Limited | Information & communication | 2023 |
| Myriad Corporation Limited | Financial services | 2020 |
| N&J Grove Ltd | Professional & scientific | 2023 |
| N3XT Door Bar Limited | Hospitality | 2025 |
| Nairn Contractors Ltd | Professional & scientific | 2019 |
| Native Roots Ltd | Wholesale & retail | 2026 |
| Native Space Properties Ltd | Real estate | 2023 |
| Natural Stone Bathrooms Limited | Construction | 2012 |
| Naturehood Stamford CIC | Education | 2025 |
| Naturespace Limited | Extraterritorial | 2020 |
| Naturespace Partnership Limited | Professional & scientific | 2017 |
| Nbits Digital Solutions Limited | Information & communication | 2026 |
| Neil Arch Design Limited | Professional & scientific | 2013 |
| NEL Woolcott Ltd | Administrative & support | 2025 |
| Nelson Clark Limited | Professional & scientific | 2024 |
| Nelsons (Butchers) Group Limited | Financial services | 2017 |
| Nelsons (Butchers) Limited | Wholesale & retail | 2017 |
| Nemuno Ltd | Professional & scientific | 2023 |
| Nevandi Limited | Real estate | 2016 |
| Neville Tilley LLP | | 2010 |
| New Horizon Flowers Holdings Limited | Financial services | 2019 |
| Newbold Verdon (Rectory Gardens) NO 2 Limited | Real estate | 2010 |
| Newton - Penstar Limited | Real estate | 2023 |
| Newtown Court (Stamford) Management Ltd | Households | 2013 |
| Next Generation Flowers Limited | Wholesale & retail | 2019 |
| Next Leap Consultancy Ltd | Professional & scientific | 2023 |
| Nextgen Trader Ltd | Wholesale & retail | 2020 |
| Nexus LCT Ltd. | Transport & logistics | 2020 |
| Nexus Roushill Management Limited | Households | 2006 |
| NGI Design Ltd | Wholesale & retail | 1997 |
| Nico Beau Group Limited | Professional & scientific | 2014 |
| Nightingales Properties Limited | Real estate | 2018 |
| Nimble Media Ltd. | Information & communication | 2013 |
| NJB Consulting Services Limited | Professional & scientific | 2008 |
| NLJ Communications Limited | Information & communication | 2017 |
| NO Need to Sugar Coat IT Ltd | Manufacturing | 2025 |
| Nocta Ltd | Wholesale & retail | 2018 |
| Noire UK Holdings Ltd | Financial services | 2023 |
| Noiretech Ltd | Financial services | 2011 |
| Noook Ltd | Professional & scientific | 2015 |
| North Norfolk Living Limited | Information & communication | 2011 |
| North ST Developments Ltd | Construction | 2012 |
| Northbank Consultancy Ltd | Professional & scientific | 2023 |
| Northern ACI Limited | Construction | 2013 |
| Nosamplio Limited | Health & social care | 2019 |
| Noughts and Crosses Stamford Ltd | Wholesale & retail | 2024 |
| NSC Solutions Limited | Transport & logistics | 2011 |
| Nyestra Ltd | Real estate | 2025 |
| Oak & Stone Stamford Ltd | Construction | 2026 |
| Oak Bespoke Construction Ltd | Construction | 2018 |
| Oakthorpe Limited | Administrative & support | 2010 |
| Obsidian Blue Limited | Professional & scientific | 2017 |
| Octopus Inc (Property) Ltd | Real estate | 2025 |
| ODE to Joy Flowers Co. Ltd | Wholesale & retail | 2023 |
| Odedra Productions Ltd | Information & communication | 2024 |
| Offerasset Limited | Administrative & support | 2025 |
| Offshorly Ltd | Information & communication | 2017 |
| OJ Holdings Ltd | Real estate | 2021 |
| Old English Company Ltd | Manufacturing | 2013 |
| Old English Doorways Limited | Manufacturing | 2026 |
| Old School Capital Limited | Real estate | 2022 |
| Oliver Neil Homes Limited | Real estate | 2009 |
| Oliver Smith Financial Management Limited | Financial services | 2013 |
| Olivers Removals & Transport Limited | Transport & logistics | 2015 |
| Olsen Media Group Ltd | Professional & scientific | 2019 |
| Olsen Partnership Limited | Real estate | 2005 |
| Olver BTL Ltd | Real estate | 2022 |
| Olver Estates Limited | Real estate | 2022 |
| OMG Enterprises Limited | Professional & scientific | 2003 |
| Omnia Building Consultants Ltd | Construction | 2025 |
| Ompt Group Limited | Information & communication | 2021 |
| OMS UK Consultants Ltd | Information & communication | 2015 |
| Onesto Limited | Construction | 2018 |
| Opal & Oak Properties Limited | Households | 2025 |
| Open Britain (Trading) Ltd | Professional & scientific | 2025 |
| Open Britain Limited | Other services | 2015 |
| Open for Vintage Limited | Wholesale & retail | 2015 |
| Ophelia Liberty Limited | Wholesale & retail | 2020 |
| Optimum Design Services Limited | Professional & scientific | 2005 |
| Options Care Day Opportunities Ltd | Health & social care | 2021 |
| Options Social CIC | Health & social care | 2023 |
| Opus Fresh Ltd | Wholesale & retail | 2018 |
| Orchard Building Contractors Ltd | Construction | 2010 |
| Orion Business Centres Limited | Real estate | 2001 |
| Osborne Innovations Ltd | Professional & scientific | 2016 |
| Osborne Smith Properties Ltd | Real estate | 2016 |
| Oscar & Harvey Limited | Administrative & support | 2025 |
| Osiris Organisational Services Limited | Professional & scientific | 1996 |
| OSS Living Ltd | Administrative & support | 2025 |
| Ostrich Feather London Limited | Manufacturing | 2005 |
| Ostrich Feather Manufacturing Company Limited | Manufacturing | 1935 |
| Otters Enterprises Ltd | Real estate | 2018 |
| Oundle Marina Village Limited | Wholesale & retail | 2011 |
| Outdoor and Tactical Limited | Wholesale & retail | 2016 |
| Outsourced Finance Office Limited | Professional & scientific | 2026 |