| NS Professional Services Ltd | Wholesale & retail | 2003 |
| NSM Properties (Wrexham) Ltd | Real estate | 2026 |
| Nsos Safety Limited | Administrative & support | 2024 |
| Ntier Solutions Ltd | Information & communication | 2025 |
| Numdar Ltd | Construction | 2024 |
| NW Property Leads Ltd | Administrative & support | 2026 |
| NW Watan Ltd | Wholesale & retail | 2025 |
| NWB Properties Limited | Real estate | 2013 |
| Nwcis Ltd | Health & social care | 2021 |
| Nwhh Limited | Hospitality | 2021 |
| Nwia Limited | Financial services | 2013 |
| Nyas Group Ltd | Administrative & support | 2024 |
| Nyilika Enterprise Limited | Health & social care | 2023 |
| Nypro (UK) Limited | Manufacturing | 1991 |
| O G Management Limited | Professional & scientific | 2002 |
| O W L Lidford Holdings Limited | Wholesale & retail | 2019 |
| O'Brien Mortgage Consultancy Ltd | Financial services | 2019 |
| O'Regan-Wallace Ltd | Manufacturing | 2025 |
| Oak Drive (Overton) Residents Management Company Limited | Administrative & support | 2017 |
| Oak Tree Lets Limited | Real estate | 2015 |
| Oak Tree Properties (Wrexham) Limited | Real estate | 2024 |
| Oakeley Design Services Holdings Limited | Financial services | 2021 |
| Oakhurst EMC Limited | Financial services | 2023 |
| Oaklands Office Park (Management) Limited | Real estate | 2007 |
| Oakorn Engineering Services Ltd | Other services | 2011 |
| Oasis Care Limited | Health & social care | 1997 |
| Oasis Tasty Food Ltd | Wholesale & retail | 2018 |
| OB Wrexham Limited | Other services | 2024 |
| Obsidian Security Solutions Limited | Other services | 2021 |
| Occasion Apps CYF. | Information & communication | 2023 |
| Ocean Hope Ltd | Hospitality | 2023 |
| Octavia Projects Limited | Construction | 2023 |
| Octopus Produce Ltd | Wholesale & retail | 2025 |
| Oddfellows Hall (CH4) Limited | Hospitality | 2023 |
| Odelle Lounge Salon Limited | Other services | 2026 |
| Odli Glamping Ltd | Hospitality | 2020 |
| Odon Escapes Ltd | Hospitality | 2026 |
| OEW Joinery and Building Ltd | Construction | 2025 |
| Off-Grid Prizes Ltd | Arts & recreation | 2022 |
| Office Village Management Company Limited | Real estate | 2003 |
| Offthegridliving Ltd | Construction | 2022 |
| OG Candy Shop Ltd | Wholesale & retail | 2024 |
| Oggie Shop (Wales) Limited | Wholesale & retail | 2014 |
| OJO Engineering Ltd | Construction | 2025 |
| Okaytix Ltd | Wholesale & retail | 2025 |
| Olbe Limited | Wholesale & retail | 2012 |
| Old Bishop's Palace Limited | Hospitality | 2017 |
| Old NO7 Bar Lounge Ltd | Hospitality | 2020 |
| Old Panda Creative Ltd | Information & communication | 2024 |
| Old Swan Wrexham Limited | Other services | 2020 |
| Oldgate Medical Limited | Professional & scientific | 2016 |
| Olga Fahey Consulting Ltd | Professional & scientific | 2018 |
| Olivia Ferrier Sculpture Ltd | Arts & recreation | 2006 |
| Ollie Parker Electrical Limited | Construction | 2026 |
| Oluderrick Properties Limited | Construction | 2023 |
| Olympus Gymnastics Club Ltd | Arts & recreation | 2015 |
| OM UK Bidco Limited | Financial services | 2023 |
| OM UK Holdco Limited | Financial services | 2023 |
| Omega Technical Services (UK) Limited | Other services | 1999 |
| Omega Thermal Insulations Limited | | 1987 |
| Omniscan Limited | Wholesale & retail | 2004 |
| ON a Mission Coaching Ltd | Health & social care | 2025 |
| ON Course Golf Ltd. | Manufacturing | 2003 |
| ON Course Solutions Ltd | Manufacturing | 2008 |
| ON Shelving Limited | Manufacturing | 2021 |
| ON the Marc Ltd | Other services | 2011 |
| ON the Verge Roofing Ltd | Construction | 2023 |
| One Group Capital Ltd | Financial services | 2024 |
| One Idea Consultancy Ltd. | Information & communication | 2015 |
| One Lane Sales and Lettings Limited | Real estate | 2024 |
| One Step Ahead FHP Ltd | Health & social care | 2024 |
| One Step Installations Limited | Construction | 2015 |
| One Stop Occupational Health Ltd | Health & social care | 2022 |
| One World Project Ltd | Information & communication | 2022 |
| Onecars Garage Ltd | Wholesale & retail | 2021 |
| Onefix Garage Ltd | Wholesale & retail | 2023 |
| Oneinvest Ltd | Real estate | 2024 |
| Oneplanet Adventure Limited | Arts & recreation | 2005 |
| Onepubs Platform Ltd | Hospitality | 2021 |
| Online Box Limited | Wholesale & retail | 2025 |
| Ontario Holding Limited | Financial services | 2016 |
| Ontario Management Limited | Financial services | 2016 |
| Onyx Plumbing & Heating Ltd | Construction | 2025 |
| Onyx Projects (NW) Ltd | Construction | 2025 |
| Open Engineering Consulting Limited | Professional & scientific | 2019 |
| Open the Box CIC | Arts & recreation | 2019 |
| Openoffice Group Ltd | Professional & scientific | 2022 |
| Optimised Projects Ltd | Other services | 2006 |
| Opulent Outdoor Living Limited | Construction | 2021 |
| OR3D Ltd | Professional & scientific | 1997 |
| Orca Business Support Limited | Administrative & support | 2010 |
| Orchard House Rental Properties Ltd | Real estate | 2017 |
| Orchard Pigs (Wales) Limited | Manufacturing | 2010 |
| OS Freight Wrexham Ltd | Transport & logistics | 2010 |
| Osalma Ltd | Health & social care | 2019 |
| Osborne and Sons Ltd | Wholesale & retail | 2014 |
| Osborne and Sons Retail Ltd | Wholesale & retail | 2019 |
| Osborne Holdings Limited | Real estate | 2022 |
| Osborne's Contract Flooring Limited | Construction | 2019 |
| Oscar Mayer Limited | Manufacturing | 1976 |