| North West Leicestershire Society of Model Engineers Ltd | Arts & recreation | 1996 |
| Northbrook (Worthing) Estate Management Company Limited | Households | 2013 |
| Norton Design and Development Ltd | Professional & scientific | 1999 |
| Noshas Limited | Wholesale & retail | 2022 |
| Nothing 2 SEE Ltd | Other services | 2022 |
| Nova Design and Marketing Ltd | Professional & scientific | 2021 |
| Nova Meridian Ltd. | Wholesale & retail | 2021 |
| Novus Lead Partners Ltd | Wholesale & retail | 2016 |
| NPE Estates Limited | Administrative & support | 2025 |
| Npwholesale Ltd | Wholesale & retail | 2023 |
| Nubian Republic Ltd | Wholesale & retail | 2024 |
| Number 9 Staffing Ltd | Administrative & support | 2014 |
| Nurturelink Care Solutions Limited | Administrative & support | 2025 |
| O'Donnell & Sons Properties Limited | Real estate | 2015 |
| Oakfield Grange (Llantarnam) Residents Management Company Ltd | Households | 2017 |
| Oakfields Residential Management Company Limited | Households | 2016 |
| Oakleigh Residential Home Limited | Health & social care | 2008 |
| Oaks Estates Ltd | Real estate | 2024 |
| Oakthorpe View Ltd | Other services | 2016 |
| OAL Investments Ltd | Real estate | 2024 |
| Obtain Automotive Ltd | Wholesale & retail | 2020 |
| OC1 Suspension Limited | Wholesale & retail | 2010 |
| OCC Group Ltd | Professional & scientific | 2025 |
| Occupation Properties Holdings Limited | Financial services | 2024 |
| Occupation Properties Limited | Real estate | 2024 |
| Octara Court (Yoxall) Management Company Limited | Households | 2026 |
| Odedra & Sullivan Properties Ltd | Real estate | 2021 |
| OES Health & Fitness Ltd | Arts & recreation | 2024 |
| Oh!My Cake! Ltd | Manufacturing | 2025 |
| Oharper Pattern Cutting Ltd | Manufacturing | 2025 |
| Ohmega Systems Limited | Professional & scientific | 2005 |
| OLB Welding Services Limited | Manufacturing | 2024 |
| Old House Consultancy U.K Ltd | Other services | 2023 |
| Old Saltleians Rugby Football Club Limited | Arts & recreation | 2012 |
| Olive Grove Estates Ltd | Real estate | 2018 |
| Olive Park Residents Management Company Limited | Households | 2022 |
| Olive Tree Hair & Beauty Ltd | Other services | 2026 |
| Oliver JH Enterprises Ltd | Wholesale & retail | 2024 |
| Onboard Couriers Limited | Transport & logistics | 2025 |
| Only Maps and Locks Ltd | Wholesale & retail | 2026 |
| Opacity One Ltd | Information & communication | 2023 |
| Opal Gate (Fladbury) Management Company Limited | Households | 2015 |
| Open House Local Limited | Real estate | 2022 |
| Operational Efficiency Limited | Transport & logistics | 2025 |
| Opmobility Exterior UK Limited | Manufacturing | 1996 |
| Optilight Windows UK Limited | Extraterritorial | 2013 |
| Optimal Lift Services Ltd | Manufacturing | 2020 |
| Oracle OT Ltd | Health & social care | 2023 |
| Orange Tree Coaching Ltd | Education | 2026 |
| Orbative Systems Ltd | Information & communication | 2026 |
| Orchard Safety Limited | Professional & scientific | 2021 |
| Oria Strategy Ltd | Administrative & support | 2023 |
| Oriel View Residents Management Company Limited | Households | 2018 |
| Orivon Ltd | Hospitality | 2020 |
| Orton, Dayton and Gilbert Ltd | Hospitality | 2022 |
| Orvitec Ltd | Manufacturing | 2025 |
| Oset Bikes Limited | Manufacturing | 2007 |
| OT Network Ltd | Health & social care | 2022 |
| Othello Accessories Limited | Wholesale & retail | 1989 |
| OUR Monkey Club C.I.C. | Education | 2010 |
| Outcry for Mercy Ltd | Information & communication | 2025 |
| Outsider Studio Ltd | Professional & scientific | 2020 |
| Overland Contracting Ltd | Construction | 2023 |
| Overseal Oriental Limited | Hospitality | 2024 |
| Overseas Assets Consultants Limited | Administrative & support | 2015 |
| O’Donnell Investment Holdings Limited | Financial services | 2026 |
| P Bunce Developments Limited | Construction | 2019 |
| P Gray & SON Limited | Construction | 2002 |
| P H Flexible Packaging Limited | Manufacturing | 1995 |
| P R Horticultural Services Limited | Manufacturing | 2003 |
| P Worth Electrical Services Ltd | Construction | 2017 |
| P. R. Gaunt Technical Services Ltd | Construction | 1998 |
| P.F. Spare (1962) Limited | Financial services | 1988 |
| P.H. Flexible Insulations Limited | Wholesale & retail | 2002 |
| P.L.G. Flooring Limited | Wholesale & retail | 2003 |
| Padel Bears Ltd | Wholesale & retail | 2024 |
| Paint Application Services Ltd | Construction | 2024 |
| Palletman Services Limited | Manufacturing | 2023 |
| Palys Transport Ltd | Transport & logistics | 2018 |
| Panda Marine Contracting Ltd | Construction | 2024 |
| Panel Prep Ltd | Manufacturing | 2024 |
| Papas Pizza and Kebab Ltd | Hospitality | 2024 |
| Papion Estates Limited | Agriculture & fishing | 2007 |
| Parbrahm Ltd | Transport & logistics | 2025 |
| Parsons Grove Residents Management Company Limited | Households | 2019 |
| Passioncare@Home Ltd | Extraterritorial | 2023 |
| Patel (UK) Retailers Limited | Construction | 2024 |
| Patel's Daily Variety Limited | Wholesale & retail | 2025 |
| Paul Bunce & Sons Limited | Administrative & support | 2003 |
| Paul Joseph Stunts Ltd | Arts & recreation | 2022 |
| Paul K Sherratt Ltd | Transport & logistics | 2019 |
| Paul Knowles Limited | Construction | 2007 |
| Paul Satchell Limited | Construction | 2002 |
| Paul Thompson Handyman Services Limited | Construction | 2002 |
| Paul Topliss (Plumbing & Heating Services) Limited | Construction | 2002 |
| Payroll Connect Limited | Professional & scientific | 2007 |
| PB Technical Consulting Ltd | Professional & scientific | 2023 |
| PD Driving School Limited | Education | 2024 |
| Pe&W H-S Limited | Professional & scientific | 2022 |
| Peak Performance Systems Ltd | Professional & scientific | 2025 |