| Nisla Ltd | Real estate | 2021 |
| Nitrogn Ltd | Information & communication | 2019 |
| NMG Holdings Limited | Real estate | 2017 |
| NO Ableism Ltd | Wholesale & retail | 2024 |
| NO.1 the Warehouse Limited | Real estate | 2025 |
| Noble Cleaning Ltd | Administrative & support | 2023 |
| Nofskywit Community Interest Company | Education | 2020 |
| Noglu Ltd | Manufacturing | 2023 |
| Noirvale Ltd | Professional & scientific | 2025 |
| Nola Cereal Ltd | Manufacturing | 2024 |
| Nomada Education Ltd | Education | 2024 |
| Northern Star Bespoke Jewellery Limited | Manufacturing | 2013 |
| Nova Crew Limited | Administrative & support | 2013 |
| Novo Architecture Ltd | Professional & scientific | 2014 |
| NSG Building Ltd | Construction | 2022 |
| Nucleus Advisors Limited | Professional & scientific | 2014 |
| NW Silver Coast Properties Limited | Extraterritorial | 2015 |
| NWG Urology Ltd | Health & social care | 2021 |
| Ocean House Management Company Limited | Real estate | 2001 |
| Ocean Properties (Cardiff) Limited | Real estate | 2018 |
| Octagon Content Ltd | Information & communication | 2020 |
| ODR Creative Design Limited | Information & communication | 2005 |
| Offshoot Consulting Ltd | Information & communication | 2019 |
| OH SO Small Productions Ltd | Arts & recreation | 2010 |
| Old Penarthians RFC Limited | Arts & recreation | 2019 |
| Olec Electrical Limited | Construction | 2014 |
| Olive Advisory and Training Limited | Professional & scientific | 2023 |
| Olro Ltd | Wholesale & retail | 2017 |
| Omega Edge Ltd | Administrative & support | 2025 |
| Omidaze Productions Ltd | Arts & recreation | 2023 |
| Omnilumen Limited | Education | 2024 |
| ON Cloud Spine Limited | Health & social care | 2024 |
| ON Trend Kitchens & Interiors Limited | Manufacturing | 2020 |
| Ondeck Consultancy Ltd | Professional & scientific | 2025 |
| One Life One Line Ltd | Information & communication | 2026 |
| Onecallwales Ltd | Information & communication | 2019 |
| Onsite Cylinder Filling Ltd | Wholesale & retail | 2026 |
| Onsite LPG Solutions Ltd | Wholesale & retail | 2026 |
| Ontik Technologies Limited | Information & communication | 2022 |
| Onzon Thai (Penarth) Limited | Hospitality | 2024 |
| Onzon Thai Limited | Hospitality | 2020 |
| Opengenius Limited | Information & communication | 2005 |
| Oral-X Ltd | Manufacturing | 2025 |
| Orbalgroup Ltd | Professional & scientific | 2023 |
| Orchard Day Nursery Penarth Limited | Health & social care | 2026 |
| Orchard Holdings Penarth Ltd | Health & social care | 2026 |
| Organic Gaia Ltd | Wholesale & retail | 2025 |
| Orogenic Consulting Ltd | Professional & scientific | 2020 |
| OSM Eight Ltd | Real estate | 2020 |
| Ovio Solutions Ltd | Construction | 2014 |
| Oyster Wharf Piazza Limited | Real estate | 2020 |
| Pace Fitness Holdings Ltd | Financial services | 2023 |
| PAD Deco Ltd | Professional & scientific | 2014 |
| Paddeco Connect Ltd | Other services | 2019 |
| Page Motors Ltd | Wholesale & retail | 2025 |
| Pageoneworld Ltd | Professional & scientific | 2016 |
| Pages Holdings Limited | Real estate | 2019 |
| Paget Partnership Limited | Real estate | 2017 |
| Palser Family Investments Limited | Financial services | 2006 |
| Park Funeral Directors Limited | Other services | 2009 |
| Part B Fire Engineering (Wales) Limited | Professional & scientific | 2022 |
| Paul Bailey Consultancy Limited | Information & communication | 2015 |
| Paul-Tech Ltd | Information & communication | 2024 |
| PAY2FISH Ltd | Information & communication | 2016 |
| Paysah Ltd. | Information & communication | 2014 |
| Peach Holdco Limited | Financial services | 2021 |
| Peats Beast Limited | Manufacturing | 2012 |
| Pecuniary Limited | Professional & scientific | 2005 |
| Pegasus Contracting Limited | Real estate | 2014 |
| Pegasus Developments (Barry) Limited | Real estate | 2018 |
| Pegasus Developments (Bridgend) Limited | Real estate | 2026 |
| Pegasus Developments (Cardiff) Limited | Real estate | 2025 |
| Pegasus Developments (Cowbridge Road) Limited | Real estate | 2016 |
| Pegasus Developments (Glamorgan) Limited | Real estate | 2018 |
| Pegasus Developments (SW) Limited | Real estate | 2026 |
| Pegasus Developments (VOG) Limited | Real estate | 2026 |
| Pegasus Holding Group Limited | Financial services | 2026 |
| Penarth Consulting Services Limited | Information & communication | 2023 |
| Penarth Denture Laboratory & Clinic Limited | Manufacturing | 2021 |
| Penarth Food Ltd | Hospitality | 2025 |
| Penarth Headland Link | Construction | 2015 |
| Penarth Homes Management Limited | Households | 1974 |
| Penarth Launderette Ltd | Administrative & support | 2026 |
| Penarth RFC Ltd | Arts & recreation | 2021 |
| Penarth Risk Management Ltd | Professional & scientific | 2024 |
| Penarth Scaffolding Company Ltd | Construction | 2015 |
| Penarth Spice Ltd | Hospitality | 2018 |
| Penarth Stone Masonry Limited | Construction | 2013 |
| Penarth Tyres Limited | Wholesale & retail | 2021 |
| Penarth View Limited | Information & communication | 2017 |
| Penarth Yacht Club Ltd | Arts & recreation | 2025 |
| Pencarreg Consultants Limited | Professional & scientific | 1995 |
| Pencerdd T/A Penarth Music Centre Ltd | Wholesale & retail | 2002 |
| Pengalia Ltd | Financial services | 2018 |
| Penn Hill Property Ltd | Real estate | 2023 |
| Peripheral Ltd | Professional & scientific | 2024 |
| Peter Wood Residential Ltd | Real estate | 2013 |
| Petit Four Patisserie Limited | Manufacturing | 2023 |
| PGP Properties Ltd | Real estate | 2020 |
| Phoneray Limited | Real estate | 2004 |