| Norvix Trading Ltd | Wholesale & retail | 2026 |
| Noticia Solutions Limited | Information & communication | 2019 |
| Nottingham Mobile Car Wash Ltd | Wholesale & retail | 2025 |
| Nottinghamshire County Rowing Ltd | Arts & recreation | 2026 |
| Nova Digital Ventures Ltd | Professional & scientific | 2024 |
| Novek Business Services Ltd | Administrative & support | 2018 |
| Npmd Cleaning Ltd | Administrative & support | 2025 |
| NPW Motors Limited | Transport & logistics | 2003 |
| NQN Trade Ltd | Wholesale & retail | 2026 |
| NR 12 Engineering Limited | Construction | 2019 |
| NR Residentials Ltd | Real estate | 2025 |
| NRG Property Services Ltd | Real estate | 2025 |
| NS Education Ltd | Construction | 2024 |
| Nskd Ltd | Hospitality | 2016 |
| Nspark Electrical Ltd | Professional & scientific | 2010 |
| Nt.Aamz Ltd | Other services | 2021 |
| NTH Distributions Ltd | Wholesale & retail | 2025 |
| NU Global Limited | Wholesale & retail | 2003 |
| NUB Creative Ltd | Information & communication | 2019 |
| Nudge Circularity Ltd | Professional & scientific | 2025 |
| Nura Driver Ltd | Transport & logistics | 2021 |
| Nuthatch Furniture Ltd | Manufacturing | 2012 |
| Nutroliq Ltd | Wholesale & retail | 2020 |
| NW Recruiting Limited | Administrative & support | 2025 |
| Nxhub Ltd | Information & communication | 2025 |
| NXT GEN Electrical Solutions Ltd | Construction | 2021 |
| O M N Insulation Services Ltd | Construction | 2022 |
| O'Donnell - Bourne Ltd | Hospitality | 2024 |
| O'Keeffe Carpentry Services Ltd | Construction | 2012 |
| Oak and Tulip Ltd | Real estate | 2026 |
| Oak Close Property Ltd | Real estate | 2023 |
| Oak Lodge Burton Ltd | Health & social care | 2016 |
| Oak Ridge Adventure Ltd | Wholesale & retail | 2018 |
| Oak Ridge Engineering Ltd | Manufacturing | 2017 |
| Oak Spice Foods Ltd | Hospitality | 2022 |
| Oasis Foods Limited | Manufacturing | 1992 |
| OB Rigging (Burton) Ltd | Construction | 2025 |
| Octavia Agencies Limited | Wholesale & retail | 2013 |
| Odedra Investment Ltd | Real estate | 2023 |
| ODT.1010 Ltd | Wholesale & retail | 2019 |
| OF2G Limited | Wholesale & retail | 2025 |
| OGT Logistics Limited | Transport & logistics | 2025 |
| OH Medica Ltd | Health & social care | 2010 |
| Ohtc Consultancy Services Ltd | Professional & scientific | 2024 |
| OJW Maintenance Limited | Administrative & support | 2016 |
| OLA Auto Ltd | Wholesale & retail | 2022 |
| OLB Properties Limited | Real estate | 2025 |
| Old IS Gold Limited | Real estate | 2015 |
| Old Midlands Riding Club Ltd | Arts & recreation | 2024 |
| Old OE Ltd | Wholesale & retail | 2023 |
| Olemar Ltd. | Administrative & support | 2016 |
| Oliver Glen Consulting Ltd | Information & communication | 1997 |
| Olivewood Investments Ltd | Financial services | 2026 |
| Olivian Limited | Information & communication | 2014 |
| Ollen Properties Ltd | Real estate | 2022 |
| OLO Direct Ltd | Wholesale & retail | 2014 |
| OMC Training and Development Ltd | Education | 2023 |
| Omnes Healing Limited | Health & social care | 2015 |
| Omnific 3D Limited | Manufacturing | 2021 |
| Omniscient Systems Management Limited | Wholesale & retail | 2008 |
| Omorfi Aesthetics Ltd | Health & social care | 2023 |
| OMV Ltd | Wholesale & retail | 2024 |
| ON Hand Training & Security Limited | Administrative & support | 2017 |
| ON My Way Haulage Ltd | Transport & logistics | 2023 |
| Onboard Consultancy Ltd | Information & communication | 2022 |
| Once OR Twice Limited | Professional & scientific | 2025 |
| Once Upon a Paper Ltd | Professional & scientific | 2024 |
| One Law Consultancy Ltd | Administrative & support | 2022 |
| One Stop Driving School Ltd | Education | 2025 |
| One-Clean (Primary) Limited | Households | 2013 |
| Onevision Aspire C.I.C. | Education | 2026 |
| Only Joking Limited | Wholesale & retail | 2012 |
| Onpoint Service Delivery Ltd | Information & communication | 2025 |
| Onside Legal Limited | Professional & scientific | 2013 |
| Opaline Catering Ltd | Hospitality | 2026 |
| Open Book International Limited | Construction | 1998 |
| Operation S.T. Ltd | Hospitality | 2025 |
| Operative Recruitment Ltd | Administrative & support | 2024 |
| Operative Solutions Limited | Professional & scientific | 2022 |
| OPT Transport UK Limited | Transport & logistics | 2025 |
| Optimise Structure Ltd | Professional & scientific | 2024 |
| Optimum Heating and Plumbing Supplies Ltd | Wholesale & retail | 2020 |
| Optimum Leadership Solutions Limited | Administrative & support | 2016 |
| Optimum Talent Group Ltd | Administrative & support | 2025 |
| Optimus Installations Limited | Construction | 2014 |
| Orange County Real Estate UK Limited | Real estate | 2020 |
| Orangetek Limited | Professional & scientific | 2008 |
| Orangutan Land Trust | Administrative & support | 2009 |
| ORC Group Ltd | Health & social care | 2022 |
| Orchard Children Homes Ltd | Health & social care | 2016 |
| Orchard EYE Developments Ltd | Construction | 2024 |
| Orchard Lodge Derby Limited | Health & social care | 2024 |
| ORCHARD-50 Limited | Professional & scientific | 2025 |
| Orchid Bloom Consultancy Limited | Professional & scientific | 2020 |
| Orchidee Marine Limited | Extraterritorial | 2009 |
| Ordizia Limited | Transport & logistics | 2022 |
| Oregano Staffard Ltd | Hospitality | 2025 |
| ORENDA2017 Ltd | Transport & logistics | 2017 |
| Orgreave Investments Limited | Financial services | 2022 |
| Original Building Solutions Limited | Construction | 2020 |