| Orston Partners LP | | 2017 |
| Orswell Management LP | | 2014 |
| Orthodox Donations LP | | 2017 |
| Orthogonal General Partner L.P. | | 2007 |
| Orthogonal Scotland L.P. | | 2008 |
| Orthopaedic World Limited | Health & social care | 2011 |
| Orthopolis Limited | Health & social care | 2018 |
| Orthosignal Holdings Limited | Information & communication | 2026 |
| Orto LP | | 2015 |
| Orton Railway Forwarding LP | | 2014 |
| Ortus Alliance LP | | 2014 |
| Orvani Ltd | Wholesale & retail | 2025 |
| Orville Design LP | | 2013 |
| Orwest Trade LP | | 2017 |
| Orynx Ltd | Information & communication | 2024 |
| Orzyn Limited | Wholesale & retail | 2026 |
| OS Global Partners L.P. | | 2014 |
| OS11 Limited | Information & communication | 2015 |
| OS1A Ltd | Real estate | 2020 |
| Osanwell Systems LP | | 2014 |
| OSC I TE - Scottish 1, LP | | 2007 |
| OSC I TE - Scottish 2, LP | | 2007 |
| OSC I UK - Scottish 1, LP | | 2009 |
| OSC Property Management & Investment Ltd | Households | 2020 |
| Oscar Agency L.P. | | 2012 |
| Oscar Beauties Ltd | Other services | 2026 |
| Oscar Business Services L.P. | | 2011 |
| Oscar Commerce L.P. | | 2014 |
| Oscar Investments Ltd | Extraterritorial | 2012 |
| Oscar Paul Clothing Ltd | Wholesale & retail | 2026 |
| Oscar Retail Limited | Wholesale & retail | 2023 |
| Oscar Services L.P. | | 2012 |
| Oscara LP | | 2014 |
| Oscars Sale Ltd | Wholesale & retail | 2025 |
| Oscl Limited | Mining & quarrying | 2021 |
| Oscus Media Limited | Information & communication | 2005 |
| Osif FP GP LLP | | 2022 |
| Osif FP LP | | 2022 |
| Oskar & Compani LP | | 2017 |
| Oskar Enterprise LP | | 2015 |
| OSM Groups Ltd | Real estate | 2023 |
| OSM Homes LP | | 2025 |
| Osnaburg LP | | 2014 |
| Osnatix Group LP | | 2018 |
| Osney Capital I FP LP | | 2024 |
| Osomeads Ltd | Professional & scientific | 2025 |
| Osprey Court Devco Limited | Health & social care | 2021 |
| Osprey Holidays (Tickets) Limited | Administrative & support | 1995 |
| Osprey Holidays Limited | Administrative & support | 1973 |
| Osprey Offshore Power (Aberdeen) Limited | Manufacturing | 2025 |
| Osprey Properties (Scotland) Limited | Construction | 2024 |
| Osquare LP | | 2014 |
| Osseti LP | | 2015 |
| Ossian Architects Ltd | Professional & scientific | 2022 |
| Ossington Design Limited | Professional & scientific | 2024 |
| Ossory Ltd | Administrative & support | 2022 |
| Ossu Media Limited | Professional & scientific | 2024 |
| OST Group LP | | 2015 |
| Osteomed Limited | Administrative & support | 1991 |
| Oster Networks LP | | 2015 |
| Ostework Systems LP | | 2015 |
| Ostia Trading LP | | 2016 |
| Ostin Group LP | | 2017 |
| Ostinvest L.P. | | 2015 |
| Ostlink Partners L.P. | | 2015 |
| Ostrero Ltd. | Professional & scientific | 2016 |
| Ostway Shipping Corp. LP | | 2013 |
| Osumare Theatre Company Ltd | Administrative & support | 2025 |
| OSW Engineering Limited | Professional & scientific | 2024 |
| OSW Holdings Limited | Financial services | 2017 |
| Oswald Donner and Company Limited | Administrative & support | 1954 |
| OT Fire Sprinkler Systems Limited | Administrative & support | 2012 |
| Otadini Limited | Real estate | 2019 |
| Otaner GRP Ltd | Wholesale & retail | 2026 |
| Otaq Aquaculture Limited | Professional & scientific | 2015 |
| Otaria Finance SP | | 2002 |
| OTB Performance Ltd | Professional & scientific | 2020 |
| Otelina Alliance LP | | 2018 |
| Other People Limited | Information & communication | 2018 |
| Otherside Line LP | | 2017 |
| Otilia & Son's Ltd | Manufacturing | 2018 |
| Otios Limited | Information & communication | 2017 |
| Otis & Carter Coffee Ltd | Manufacturing | 2021 |
| Otiswell Services LP | | 2012 |
| Otobo Corp Limited | Real estate | 2010 |
| Otobodocs Ltd | Financial services | 2024 |
| Otra Cleaning Services Ltd | Administrative & support | 2026 |
| Otta Home Ltd | Wholesale & retail | 2025 |
| Ottava Holdings Ltd | Information & communication | 2022 |
| Ottawa Capital Services LP | | 2013 |
| Ottawa Commerce LP | | 2015 |
| Ottawa Trading LP | | 2012 |
| Otter Forest Limited | Other services | 2021 |
| Otter Holding LP | | 2016 |
| Otterleigh Consulting Ltd | Professional & scientific | 2026 |
| Otterly Cosmetics Ltd | Wholesale & retail | 2026 |
| Otterston Properties Limited | Construction | 1991 |
| Ottilian Ltd | Health & social care | 2020 |
| Otto & Bear's Letters Ltd | Information & communication | 2026 |
| Otto Consult Holding LP | | 2019 |