| Omega Intervention Limited | Manufacturing | 2014 |
| Omega Pressure Control Equipment Limited | Administrative & support | 2018 |
| Omega Property Collection Limited | Construction | 2018 |
| Omega Safety Services Consultancy Ltd | Professional & scientific | 2026 |
| Omega Technical Subsea Services Ltd | Professional & scientific | 2025 |
| Omega Well Intervention Limited | Mining & quarrying | 1998 |
| OMF Property Ltd | Real estate | 2022 |
| Omicroneta Ltd | Information & communication | 2013 |
| OML2 Ltd | Hospitality | 2024 |
| Omni Subsea Limited | Administrative & support | 2022 |
| Omnienergy Consulting Ltd | Professional & scientific | 2025 |
| Omnira Software International Ltd | Information & communication | 2006 |
| Omniscient Safety Innovations Group Ltd | Other services | 2025 |
| Omniscient Safety Innovations Ltd | Public administration | 2018 |
| Omotenashi Rocks Ltd | Hospitality | 2018 |
| ON Purpose Ltd. | Professional & scientific | 2003 |
| ON the Edge Access Ltd. | Administrative & support | 2006 |
| Onarach & Gedeel Limited | Real estate | 2024 |
| Onboard Global Solutions Limited | Administrative & support | 2010 |
| Onbrand Studios Limited | Information & communication | 2025 |
| Once Upon a Question Ltd | Manufacturing | 2025 |
| Ondo Catering Ltd | Hospitality | 2023 |
| One 1 OFF Limited | Manufacturing | 2022 |
| One Call Limited | Construction | 1994 |
| One Day Answer Ltd | Professional & scientific | 2025 |
| One Design Aberdeen Limited | Professional & scientific | 2024 |
| One Devanha Gardens Ltd | Real estate | 2015 |
| One Digital & Entrepreneurship Limited | Real estate | 2018 |
| One Drop Skincare Ltd | Health & social care | 2025 |
| One Energy Limited | Professional & scientific | 2015 |
| One Plaice Limited | Agriculture & fishing | 2014 |
| One Stop (Property Maintenance) Limited | Construction | 1996 |
| One Stop Waste Solutions Limited | Water & waste | 2006 |
| One-Dyas EOG Limited | Mining & quarrying | 1902 |
| One-Dyas Mariner Limited | Mining & quarrying | 2013 |
| One-Dyas North Sea Limited | Mining & quarrying | 2005 |
| Onedecom Ltd | Information & communication | 2019 |
| Onemedical Group Scotland Limited | Health & social care | 2021 |
| Onesoft Solutions Limited | Information & communication | 2022 |
| Ongc Ltd | Professional & scientific | 2024 |
| Online Cables (Scotland) Limited | Administrative & support | 2018 |
| Online Electronics Limited | Manufacturing | 1996 |
| Online Group Holdings Ltd | Administrative & support | 2022 |
| Online Valves Holdings Limited | Wholesale & retail | 2016 |
| Online Valves Limited | Wholesale & retail | 2011 |
| Only CNC Ltd | Manufacturing | 2025 |
| Onlyrads Ltd | Construction | 2025 |
| Onne Services Limited | Information & communication | 2025 |
| Onomz Investment Ltd | Other services | 2025 |
| Onta Ltd | Other services | 2019 |
| Onyx Global Property Ltd | Households | 2025 |
| Onyx Interior Design Limited | Professional & scientific | 2024 |
| OOR Wullie Limited | Hospitality | 2017 |
| Opal House Beauty Ltd | Other services | 2026 |
| Open Road Limited | Arts & recreation | 2015 |
| Open Word Limited | Information & communication | 2002 |
| Operational Delivery Improvement Ltd | Information & communication | 2026 |
| Operations and Project Management Consulting Services Limited | Professional & scientific | 2022 |
| Opes Partners Ltd | Professional & scientific | 2010 |
| Ophir Gold Standard Estates Ltd | Real estate | 2026 |
| Ophir Holdings Ltd | Wholesale & retail | 2026 |
| Opito (Qualifications) Limited | Education | 1990 |
| Opito Enterprises Limited | Administrative & support | 2011 |
| Opito Group Limited | Administrative & support | 2010 |
| Opito Limited | Education | 1994 |
| Opito Training Management Limited | Administrative & support | 2003 |
| OPL Engineering Limited | Professional & scientific | 2025 |
| Opportunity North East Limited | Administrative & support | 2015 |
| Optical Limited | Extraterritorial | 1984 |
| Optihearts Limited | Health & social care | 2023 |
| Optima Process Solutions Limited | Mining & quarrying | 2023 |
| Optima Solutions Holdings Limited | Administrative & support | 2007 |
| Optima Solutions UK Limited | Mining & quarrying | 1999 |
| Optimacura Surgical Limited | Health & social care | 2024 |
| Optimal Asset Maintenance Solutions Ltd | Professional & scientific | 2016 |
| Optimum Doors Ltd | Wholesale & retail | 2017 |
| Optimum Garage Doors Ltd | Construction | 2021 |
| Optimum Nutrition Emea Limited | Professional & scientific | 1984 |
| Optiwells Ltd | Professional & scientific | 2018 |
| Opus Commercial Properties 2026 Limited | Real estate | 2026 |
| Opus Commercial Properties Limited | Real estate | 2018 |
| OR Creative Ltd | Administrative & support | 2016 |
| Orafarm Limited | Professional & scientific | 2025 |
| Oral Health Ventures Ltd | Financial services | 2025 |
| Orange DOT Developments Limited | Real estate | 2007 |
| Orbis Energy Innovations Ltd | Construction | 2019 |
| Orbis Index Ltd | Manufacturing | 2022 |
| Orbital Ocean Weld (UK) Ltd | Professional & scientific | 2026 |
| Orchard Barber Shop Ltd | Other services | 2024 |
| Orchard Properties (Aberdeen) Ltd | Real estate | 2024 |
| ORD Marketing Group Limited | Professional & scientific | 2026 |
| Ordermodern Limited | Real estate | 2001 |
| Ordinatus Insight Limited | Health & social care | 2026 |
| Ordtta Solutions Ltd | Wholesale & retail | 2023 |
| Oregon Contract Management Limited | Construction | 1998 |
| Oregon Timber Frame Ltd. | Manufacturing | 1997 |
| OREMA2 Ltd | Professional & scientific | 2023 |
| Oressaare LP | | 2013 |
| Organic Potato Growers (Scotland) Limited | Administrative & support | 2001 |
| Organica J Ltd | Manufacturing | 2023 |