| Ocean City Autos Ltd | Wholesale & retail | 2024 |
| Ocean City Bids Limited | Professional & scientific | 2023 |
| Ocean City Biodiversity Limited | Administrative & support | 2023 |
| Ocean City Boat Sales Limited | Wholesale & retail | 2024 |
| Ocean City Boxing and Fitness Academy Ltd | Arts & recreation | 2023 |
| Ocean City Builders Ltd | Construction | 2024 |
| Ocean City Bulls Ltd | Wholesale & retail | 2022 |
| Ocean City Carpentry Limited | Manufacturing | 2024 |
| Ocean City Chiropractic Limited | Health & social care | 2023 |
| Ocean City Cleaning Ltd | Administrative & support | 2025 |
| Ocean City EPC Limited | Real estate | 2025 |
| Ocean City Finance Ltd | Financial services | 2025 |
| Ocean City GAS Ltd | Extraterritorial | 2021 |
| Ocean City Heating Ltd | Construction | 2022 |
| Ocean City Holdings Ltd | Real estate | 2021 |
| Ocean City Holiday Homes Limited | Hospitality | 2025 |
| Ocean City Homes Ltd | Real estate | 2017 |
| Ocean City Inspections Ltd | Administrative & support | 2019 |
| Ocean City Labs Limited | Information & communication | 2026 |
| Ocean City Lettings Ltd | Real estate | 2025 |
| Ocean City Logistics Ltd | Transport & logistics | 2022 |
| Ocean City Marina Limited | Wholesale & retail | 2017 |
| Ocean City Marine Surveyors Ltd | Administrative & support | 2018 |
| Ocean City Media Ltd | Information & communication | 2020 |
| Ocean City Motors Limited | Wholesale & retail | 2020 |
| Ocean City Nature | Administrative & support | 2023 |
| Ocean City Partners Limited | Administrative & support | 2019 |
| Ocean City Properties Ltd | Real estate | 2024 |
| Ocean City Property Lets Ltd | Real estate | 2022 |
| Ocean City Property Ltd | Real estate | 2016 |
| Ocean City Property Services Ltd | Administrative & support | 2026 |
| Ocean City Radio Community Interest Company | Information & communication | 2020 |
| Ocean City Refinishers Ltd | Wholesale & retail | 2025 |
| Ocean City Scaffolding Ltd | Construction | 2022 |
| Ocean City Services Ltd | Administrative & support | 2025 |
| Ocean City South West Holdings Limited | Financial services | 2021 |
| Ocean City Therapy Limited | Health & social care | 2021 |
| Ocean City Windows and Doors Ltd | Construction | 2023 |
| Ocean Conservation Trust Limited | Arts & recreation | 1991 |
| Ocean Discovery Yachts Limited | Manufacturing | 2022 |
| Ocean Dudes Limited | Other services | 2015 |
| Ocean Electrics Group Ltd | Professional & scientific | 2016 |
| Ocean Electrics South West Ltd | Construction | 2014 |
| Ocean Group Marine Ltd | Agriculture & fishing | 2017 |
| Ocean Holiday Appartment Ltd | Hospitality | 2019 |
| Ocean Lets Ltd | Real estate | 2021 |
| Ocean M&E Services Ltd | Construction | 2016 |
| Ocean Mediation Limited | Other services | 2026 |
| Ocean PAY Ltd | Information & communication | 2019 |
| Ocean Property Care Ltd | Administrative & support | 2024 |
| Ocean Property Holding Company Ltd | Real estate | 2020 |
| Ocean Property Solutions Ltd | Real estate | 2019 |
| Ocean Publishing Prints Limited | Information & communication | 2008 |
| Ocean Recruitment Solutions Ltd | Administrative & support | 2019 |
| Ocean Star Media Ltd | Professional & scientific | 2018 |
| Ocean View (SW) Ltd | Hospitality | 2018 |
| Ocean View Events Ltd | Arts & recreation | 2025 |
| Ocean View Homes Ltd | Construction | 2023 |
| Ocean View Windows Ltd | Construction | 2022 |
| Oceanic Drifter Fishing Ltd | Agriculture & fishing | 2013 |
| Oceanic Marine Group Limited | Financial services | 2021 |
| Oceanic Mirage Fisheries Limited | Agriculture & fishing | 2023 |
| Oceanic Seafood South West Limited | Wholesale & retail | 2021 |
| Oceannrg (Plymouth) Limited | Energy | 2024 |
| Oceanvape RM Ltd | Wholesale & retail | 2018 |
| Oclo Developments Ltd | Real estate | 2024 |
| Oclo Offshore Ltd | Agriculture & fishing | 2020 |
| OCP Retail Limited | Wholesale & retail | 2019 |
| Ocra Limited | Households | 1994 |
| Octagon House Limited | Households | 2022 |
| Octagon Marine Limited | Manufacturing | 2021 |
| Octorisk UXO Solutions Ltd | Professional & scientific | 2026 |
| Ocvp Ltd | Professional & scientific | 2024 |
| Odds & Sprogs Ltd | Information & communication | 2018 |
| Odix Swift Services Ltd | Information & communication | 2024 |
| Odyssey Entertainment Limited | Arts & recreation | 2021 |
| Office Stonehouse Limited | Hospitality | 2018 |
| Offshore Inspection Limited | Administrative & support | 2020 |
| Offshore Marine Consultant Ltd | Professional & scientific | 2022 |
| Offshore Yacht Solutions Limited | Manufacturing | 2020 |
| Ogalo Legal Practice Ltd | Professional & scientific | 2025 |
| Ogalo Legal Services Ltd | Professional & scientific | 2015 |
| Oggy Oggy Derriford Limited | Hospitality | 2023 |
| Ogwell Eucalyptus Ltd | Financial services | 2022 |
| OHG Building Services Ltd | | 2012 |
| Ohhdesign Ltd | Professional & scientific | 2023 |
| Ohmytoppers Ltd | Wholesale & retail | 2021 |
| Oishi Sushi Restaurant Limited | Hospitality | 2020 |
| OJC Consulting Limited | Information & communication | 2015 |
| Ojmg Services Limited | Professional & scientific | 2026 |
| Ojwins Integrated Services Ltd | Wholesale & retail | 2024 |
| Olaforgod Limited | Health & social care | 2022 |
| Olare Learning Limited | Information & communication | 2025 |
| Old Chapel Lane NO2 Management Limited | Real estate | 2017 |
| Old Dairy (Management Company) Plymouth Limited(The) | Households | 1986 |
| Old Newnham Farm 2026 Limited | Households | 2026 |
| Olem Tech Ltd | Professional & scientific | 2025 |
| Olgico Limited | Financial services | 2022 |
| Olimbe Holdings Limited | Financial services | 2023 |
| Olive Marketing Limited | Professional & scientific | 2023 |