| Mroz Eyewear Ltd | Wholesale & retail | 2024 |
| MRT Office Services Ltd | Administrative & support | 2016 |
| MS Print Services Limited | Administrative & support | 2017 |
| MSS Alarms Limited | Administrative & support | 2014 |
| MTB Engineering Ltd | Manufacturing | 2022 |
| MUG & Bite Cafe Ltd | Hospitality | 2025 |
| Munchy Foods Ltd | Hospitality | 2025 |
| MW Property Developments Ltd | Construction | 2025 |
| MWM Hairdressing Ltd | Other services | 2025 |
| My Heating Expert Ltd | Construction | 2019 |
| My Magic Touch Ltd | Health & social care | 2018 |
| My Master Builder Ltd | Arts & recreation | 2024 |
| My Spare Time Limited | Construction | 2012 |
| Mynxtproperty Limited | Real estate | 2025 |
| N C F Architectural Ironmongery & Fixings Ltd. | Wholesale & retail | 2009 |
| N D Price Limited | Extraterritorial | 2022 |
| N Smith Heating and Plumbing Ltd | Construction | 2011 |
| NAK Retail Limited | Wholesale & retail | 2017 |
| Natasha Guitars UK Ltd | Wholesale & retail | 2026 |
| National Safeguarding Awards Ltd | Health & social care | 2023 |
| Natura and Sens Ltd | Manufacturing | 2023 |
| Natura Work Limited | Manufacturing | 2026 |
| Nature on the Go Ltd | Hospitality | 2025 |
| Navah Ltd | Professional & scientific | 2016 |
| NDC Global Ltd | Professional & scientific | 2013 |
| Needs Building Ltd. | Construction | 2003 |
| Nelore Steak House Limited | Hospitality | 2022 |
| NEO Project Management Ltd | Professional & scientific | 2023 |
| Netbel Holdings Limited | Manufacturing | 2015 |
| Netserveit Ltd | Information & communication | 2008 |
| Neuma Pilates Ltd | Arts & recreation | 2025 |
| New England Services Ltd | Real estate | 2018 |
| New Habitat Ltd | Real estate | 2017 |
| New Page Property Ltd | Real estate | 2018 |
| Newhaven Homes Ltd | Real estate | 2019 |
| Newmarket Premixes Limited | Administrative & support | 1998 |
| Next Door Consulting Limited | Professional & scientific | 2002 |
| Nextgenmedical Ltd | Professional & scientific | 2023 |
| NIC Aviation Limited | Professional & scientific | 2016 |
| Nice Brothers Limited | Construction | 2011 |
| Nice Solutions(Uk) Ltd | Construction | 2018 |
| Nigel Brand Builders Limited | Construction | 2005 |
| Nigel Valentine Associates Limited | Professional & scientific | 2018 |
| NJJ Estimating and Surveying Ltd | Professional & scientific | 2024 |
| NJL Joinery Limited | Manufacturing | 2012 |
| NK Thai Ltd | Hospitality | 2024 |
| NLT Kirby Limited | Agriculture & fishing | 2021 |
| Nonstopdiag Ltd | Manufacturing | 2024 |
| Norcom Technology Limited | Information & communication | 1990 |
| Nori Nori Limited | Hospitality | 2023 |
| Nosmoke Limited | Manufacturing | 2024 |
| Notes Candle Co. Ltd | Extraterritorial | 2021 |
| Notley Fitness Ltd | Financial services | 2023 |
| Novina Ltd | Agriculture & fishing | 2024 |
| Noviq Holdings Limited | Financial services | 2026 |
| Nrcj Limited | Hospitality | 2016 |
| Ntec Motorsport Ltd | Manufacturing | 2006 |
| Nudoh Developments Limited | Construction | 2019 |
| Nulands Strategic Ltd | Professional & scientific | 2015 |
| Nutmeg (Long Melford) Limited | Wholesale & retail | 2007 |
| Nuts About Miniatures Ltd | Wholesale & retail | 2023 |
| O & S Associates Limited | Professional & scientific | 2019 |
| Oak Tree Paddock Ltd | Real estate | 2011 |
| Oakhill Asset Management Ltd | Professional & scientific | 2011 |
| OCL Management Limited | Professional & scientific | 2017 |
| OD Capital Limited | Professional & scientific | 2021 |
| OFD Fire Protection Limited | Construction | 2014 |
| Ogardy Limited | Construction | 2005 |
| OJW Construction Services Limited | Construction | 2016 |
| Oliver's Management Limited | Households | 2026 |
| Omakase Sushi Limited | Hospitality | 2023 |
| Online Security Solutions Ltd | Professional & scientific | 2010 |
| OPA Health Ltd | Health & social care | 2016 |
| Opal Clean Ltd | Administrative & support | 2024 |
| Opticode Ltd | Information & communication | 2022 |
| Oracle Consulting Ltd | Professional & scientific | 2012 |
| Orange Kite Cleaning Solutions Limited | Administrative & support | 2025 |
| Orchard Estates Holdings Ltd | Financial services | 2026 |
| Orchard Estates Trading Ltd | Real estate | 2026 |
| Orchard Farm Holdings Ltd | Financial services | 2026 |
| Orchard Management (Pebmarsh) Limited | Professional & scientific | 2007 |
| Orchard Pet Supplies Ltd | Wholesale & retail | 2011 |
| Oswick Ltd | Real estate | 2013 |
| Overland Monkey Ltd | Agriculture & fishing | 2023 |
| OWL and Monkey Fulfillment Ltd | Transport & logistics | 2026 |
| P & F Cladding Limited | Construction | 2011 |
| P Christy Services Limited | Construction | 2010 |
| P J B Essex Limited | Construction | 2020 |
| P R Autos Essex Ltd | Wholesale & retail | 2024 |
| P&D Decorators (UK) Ltd | Construction | 2014 |
| P1 Autos Limited | Wholesale & retail | 2019 |
| P2P Consulting & Development Ltd | Professional & scientific | 2023 |
| Packing Shed Theatre CIC | Arts & recreation | 2016 |
| Pada Associates Limited | Real estate | 2012 |
| Paintworx Vehicle Refinishers Ltd | Extraterritorial | 2014 |
| Paladin Events Management Ltd | Administrative & support | 2025 |
| Pallad Kitchen & Bar Ltd | Hospitality | 2024 |
| Pallad Motors Ltd | Wholesale & retail | 2024 |
| Panfield Developments Limited | Agriculture & fishing | 1998 |
| Papa Push Limited | Administrative & support | 2017 |