| NRB Trading Ltd | Households | 2024 |
| NRG Electrical Installation Services Ltd | Construction | 2023 |
| NS Brickwork Ltd | Construction | 2015 |
| NS Plumbing Ltd | Construction | 2020 |
| NS Sign Installations Ltd | Construction | 2017 |
| NS Triathlon Coaching Ltd | Arts & recreation | 2024 |
| NSG Properties (UK) Ltd | Real estate | 2018 |
| NSS Data & Electrics Ltd | Construction | 2021 |
| NT Kitchens & Joinery Limited | Manufacturing | 2022 |
| NTL Property Limited | Real estate | 2025 |
| NU Direction LLP | | 2005 |
| NU Tax and Accountancy Services Limited | Professional & scientific | 2021 |
| NU Venus Consulting Ltd | Professional & scientific | 2021 |
| Nu-Agane Car Paints Limited | Wholesale & retail | 2008 |
| Nu-Eco Heat Ltd | Construction | 2021 |
| Nudge HR Ltd | Professional & scientific | 2023 |
| Nueva International Limited | Wholesale & retail | 2026 |
| Nugem Limited | Wholesale & retail | 2024 |
| Nugloze Co Limited | Health & social care | 2023 |
| Nulade Limited | Real estate | 1961 |
| Nuleaf London Limited | Professional & scientific | 2025 |
| Number 8 Homes (Design & Build) Ltd | Construction | 2022 |
| Number 8 Homes (Hartington) Ltd | Construction | 2022 |
| Number 8 Homes Limited | Construction | 2010 |
| Number 8 Partners Limited | Administrative & support | 2013 |
| Numbots Limited | Extraterritorial | 2022 |
| NUR Automotive Limited | Wholesale & retail | 2026 |
| Nursery Garden Group Ltd | Wholesale & retail | 2019 |
| Nurture ED Ltd | Information & communication | 2025 |
| Nurture Therapeutic Support Ltd | Health & social care | 2024 |
| Nurturing Childhoods Limited | Professional & scientific | 2020 |
| Nurturly Ltd | Information & communication | 2026 |
| Nurun Limited | Health & social care | 2014 |
| Nurun Nessa Sons Limited | Real estate | 2021 |
| Nurun Properties Limited | Real estate | 2023 |
| Nusica Transport Ltd | Transport & logistics | 2023 |
| Nutcellars Limited | Wholesale & retail | 2019 |
| Nutripunkt Ltd | Manufacturing | 2017 |
| Nutty Professor Limited | Manufacturing | 2022 |
| Nuvue Windows & Doors Ltd | Construction | 2019 |
| NV Spa and Wellness Limited | Other services | 2025 |
| NVM Healthcare Ltd | Health & social care | 2017 |
| NVM Transport Ltd | Transport & logistics | 2016 |
| NVP Transport Logistic Limited | Transport & logistics | 2014 |
| NW Installations Ltd | Construction | 2022 |
| NW Pro Limited | Information & communication | 2012 |
| NWE Accounting Services Limited | Professional & scientific | 2012 |
| NWW and Probate Ltd | Professional & scientific | 2026 |
| Nyaruwanga Limited | Health & social care | 2016 |
| Nycrown Estates Limited | Real estate | 2002 |
| Nycteris Ltd | Arts & recreation | 2013 |
| Nymfodora Andrea Ornithari Services Ltd | Administrative & support | 2021 |
| Nyon Consulting Ltd | Professional & scientific | 2026 |
| Nysa Management Consultancy Limited | Administrative & support | 2011 |
| O & R Installations Limited | Construction | 2025 |
| O Connor Accounting Services Ltd | Professional & scientific | 2015 |
| O EZE Therapy Ltd | Other services | 2024 |
| O Level Films Ltd | Information & communication | 2015 |
| O ZEB Mpharm Services Ltd | Health & social care | 2015 |
| O&H Property Partners Ltd | Real estate | 2025 |
| O&M Curated Supplements Ltd | Wholesale & retail | 2024 |
| O&T General Construction Ltd | Construction | 2023 |
| O'Brien Motorsport Limited | Arts & recreation | 2009 |
| O'Briens Development Ltd | Construction | 2005 |
| O'Dell Transport Limited | Transport & logistics | 1999 |
| O'Halloran Consultants Ltd | Professional & scientific | 2015 |
| O'Neill Fitness Ltd | Arts & recreation | 2020 |
| O'Shea Accident Management Ltd | Wholesale & retail | 2020 |
| O.Sargeant Landscapes Ltd | Administrative & support | 2026 |
| O1NK Limited | Information & communication | 2005 |
| O2MY Consulting Ltd | Professional & scientific | 2024 |
| OA Entertainment Ltd | Professional & scientific | 2025 |
| OAB Consultancy LLP | | 2012 |
| OAB Consultancy Solutions Ltd | Information & communication | 2019 |
| Oak Emporium Ltd | Professional & scientific | 2019 |
| Oak Fostering Limited | Health & social care | 2016 |
| Oak Gate Joinery Limited | Manufacturing | 2009 |
| Oak House Barn Limited | Construction | 2024 |
| Oak Housing Group CIC | Hospitality | 2021 |
| Oak IP Limited | Construction | 2010 |
| Oakapple Educational Services C.I.C. | Education | 2025 |
| Oakbridge Healthcare Limited | Health & social care | 2014 |
| Oakley Aviation Consultants Limited | Education | 2016 |
| Oakley Car Wash Limited | Wholesale & retail | 2025 |
| Oakley Garage (Bedford) Limited(The) | Wholesale & retail | 1964 |
| Oakley Holdings (Beds) Limited | Financial services | 2025 |
| Oakley House Holdings Limited | Extraterritorial | 2013 |
| Oakley Plant Hire Ltd | Wholesale & retail | 2021 |
| Oakley Projects (Beds) Ltd | Construction | 2025 |
| Oakley Properties (Bedford) Limited | Real estate | 1940 |
| Oakley Property Holdings Ltd | Real estate | 2026 |
| Oakley Road Property Limited | Real estate | 2006 |
| Oakley Village Cars Limited | Wholesale & retail | 2021 |
| Oakmore Property Ltd | Real estate | 2020 |
| Oakspire Group Ltd | Manufacturing | 2025 |
| Oakster Holdings Ltd | Real estate | 2014 |
| Oakvale Associates Ltd | Real estate | 2023 |
| Oakvale Partners Ltd | Real estate | 2024 |
| Oakview Associates Ltd | Professional & scientific | 2026 |
| Oakwell Commerce Ltd | Wholesale & retail | 2026 |