| Novem Ltd | Information & communication | 2007 |
| Novogenics Limited | Other services | 2025 |
| Novuprox Ltd | Information & communication | 2026 |
| Nowsignage Ltd | Information & communication | 2013 |
| Noza Ltd | Professional & scientific | 2005 |
| NQB Cybersecurity Solutions Limited | Information & communication | 2024 |
| NQB International Limited | Professional & scientific | 2016 |
| NRB Plant Hire and Properties Limited | Real estate | 2020 |
| NRB Surfacing & Groundworks Limited | Construction | 2021 |
| NS Care Group Ltd | Health & social care | 2026 |
| NS Cheema Ltd | Real estate | 2023 |
| NS Group Software Technologies Ltd | Wholesale & retail | 2022 |
| NSC MCR Ltd | Wholesale & retail | 2024 |
| Nuco Travel Ltd | Information & communication | 2011 |
| Nuera Medical Consulting Ltd | Health & social care | 2023 |
| Nunu&Farah Ltd | Wholesale & retail | 2022 |
| Nuovo Health Ltd | Health & social care | 2024 |
| Nura Medical Ltd | Education | 2026 |
| NUS Enterprise Limited | Real estate | 2015 |
| Nutristrong Ltd | Manufacturing | 2025 |
| Nuttall Holdings Limited | Administrative & support | 2023 |
| Nvap Property Limited | Real estate | 2024 |
| NW Traders Ltd | Wholesale & retail | 2019 |
| Nwai Ltd | Wholesale & retail | 2023 |
| NYA Property Limited | Real estate | 2024 |
| O & O Electrical & Builders Limited | Construction | 2022 |
| O&N Vision Limited | Health & social care | 2017 |
| O3 Solutions Ltd | Wholesale & retail | 2022 |
| Oak Compliance Consultancy Limited | Administrative & support | 2022 |
| Oak Meadows Management Company Limited | Real estate | 2015 |
| Oakdale Care Services Ltd | Health & social care | 2026 |
| Oakes Design & Build Ltd | Construction | 2022 |
| Oakhill Lodge Limited | Extraterritorial | 2021 |
| Oakhill W Limited | Extraterritorial | 2022 |
| Oakistic Ltd | Professional & scientific | 2022 |
| Oakleigh House (Sale) Management Company Limited | Households | 2011 |
| Oaktree Cottages (Management) Limited | Households | 1985 |
| Oakwater Holdings Limited | Professional & scientific | 2020 |
| Oakwood (Ollerton) Management Company Limited | Households | 2025 |
| Oasis Adolescent Services Limited | Health & social care | 2017 |
| Oasis Research Community C.I.C. | Professional & scientific | 2025 |
| OBH 3 Ltd | Real estate | 2024 |
| Objet-Fg Solutions Limited | Other services | 2017 |
| Oblivius Ltd | Wholesale & retail | 2025 |
| OC Legal Ltd | Professional & scientific | 2026 |
| Occurent Ltd. | Real estate | 2025 |
| Ocean Pacific Travels & Tours Ltd | Administrative & support | 2024 |
| Ocean Pharma Ltd | Professional & scientific | 2013 |
| Oceangate Limited | Real estate | 2023 |
| Octagon Residential Properties Ltd | Extraterritorial | 2026 |
| Octane Services Ltd | Professional & scientific | 2018 |
| Octo Creative Limited | Professional & scientific | 2016 |
| Offbeat Tanning Ltd | Other services | 2024 |
| OH Kiss Ltd | Wholesale & retail | 2019 |
| OH My Smile Limited | Health & social care | 2017 |
| OH YES Toys Ltd | Wholesale & retail | 2025 |
| Ohmzy Homes Ltd | Real estate | 2019 |
| Ohmzy Limited | Real estate | 2022 |
| Oikos Investments | Financial services | 2020 |
| OK Drinks Ltd | Wholesale & retail | 2021 |
| OK Investments Manchester Limited | Real estate | 2017 |
| OK Medical Services (Manchester) Limited | Health & social care | 2010 |
| OK Soda Ltd | Manufacturing | 2025 |
| OLB Homes Limited | Real estate | 2017 |
| Olbopo Property UK Ltd | Real estate | 2025 |
| Olbopo UK Ltd | Professional & scientific | 2018 |
| Olcer Consultancy Ltd | Wholesale & retail | 2023 |
| Old English Jewellers Limited | Other services | 2017 |
| Old Lansdowne Road (Manchester) RTM Company Limited | Households | 2018 |
| Oldschoolgarms Ltd | Wholesale & retail | 2025 |
| Oleva and Associates Ltd | Manufacturing | 2015 |
| Olivarch Limited | Information & communication | 2024 |
| Olive Tree Baking Ltd | Hospitality | 2018 |
| Oliver Engineering Services Ltd | Professional & scientific | 1995 |
| Oliver Lloyd Ltd | Professional & scientific | 2025 |
| Olivetree Medical Services Ltd. | Health & social care | 2014 |
| Ollie Aspin Padel Academy Limited | Arts & recreation | 2025 |
| Olympian Fire Protection Limited | Construction | 1991 |
| Olympusoft Limited | Information & communication | 2025 |
| Omer ET Tasty Catering Ltd | Hospitality | 2021 |
| Omnis VAT Consultants Ltd | Professional & scientific | 2009 |
| Omrex Ltd | Professional & scientific | 2025 |
| ON Rock Property Limited | Real estate | 2020 |
| One Aber Ltd | Health & social care | 2025 |
| One and ALL Wealth Management Ltd | Financial services | 2012 |
| One Essential Basket Ltd | Wholesale & retail | 2025 |
| One Goal Ltd | Education | 2010 |
| One Goal UK Ltd | Arts & recreation | 2021 |
| One Stop Building Solutions Limited | Construction | 2010 |
| Onebrook Group Ltd | Administrative & support | 2026 |
| Onesky Restaurant Ltd | Hospitality | 2018 |
| Onestead Limited | Real estate | 2020 |
| Onex Transport Ltd | Transport & logistics | 2020 |
| Onist Marketing Ltd | Professional & scientific | 2023 |
| Online Administration Services Limited | Professional & scientific | 2025 |
| Online Mall Ltd | Wholesale & retail | 2020 |
| Online Success Ltd | Extraterritorial | 2016 |
| Onpoint Supply Services Ltd | Professional & scientific | 2024 |
| Onside Roofing Ltd | Construction | 2025 |
| Onyx UK Consultancy Ltd | Professional & scientific | 2019 |