| Old Market Square Management Company Limited | Households | 2008 |
| Onbrief.Ai Ltd | Information & communication | 2025 |
| One Fairways Limited | Hospitality | 2023 |
| One L Productions Ltd | Arts & recreation | 2018 |
| One L Studios Ltd | Manufacturing | 2020 |
| Oopsy Daisy Holywood Limited | Health & social care | 2021 |
| Oraone Ltd | Construction | 2025 |
| ORB Films Ltd | Information & communication | 2016 |
| Orca Studios Ltd | Information & communication | 2016 |
| Orion DUO | Arts & recreation | 1990 |
| Orrs Butchers Holywood Limited | Wholesale & retail | 2022 |
| Orthopaedic Healthcare Limited | Other services | 2022 |
| Oscar & Joy Limited | Wholesale & retail | 2015 |
| Osteoblast Ltd | Health & social care | 2015 |
| OUR Fashion FIX Ltd | Other services | 2023 |
| Outwalker Limited | Manufacturing | 2021 |
| Outwork Social Ltd | Information & communication | 2025 |
| OVA Lifestyle Limited | Other services | 2017 |
| Over the Hedge Wraparound CIC | Health & social care | 2020 |
| Owens Trading Ltd | Financial services | 2021 |
| Owlpig Ltd | Information & communication | 2018 |
| Oystercatcher Talent Ltd | Administrative & support | 2025 |
| P&L DEV NI Limited | Construction | 2025 |
| P.L. Worth Learning Ltd | Education | 2018 |
| P13RV Limited | Real estate | 2022 |
| P1HTE Holdings Ltd | Financial services | 2024 |
| Pacific Wharf Limited | Other services | 2002 |
| Packaging Solutions Ireland Limited | Administrative & support | 2023 |
| Packpro (CS) Limited | Other services | 2025 |
| Paiwe Ltd | Information & communication | 2024 |
| Paleo Pines Ltd | Information & communication | 2019 |
| Paperchain Jewellery Ltd | Wholesale & retail | 2013 |
| PB Couriers Limited | Transport & logistics | 2015 |
| PDK Associates Ltd | Administrative & support | 2015 |
| Peace and Reconciliation Partners Ltd | Professional & scientific | 2026 |
| Pearl Capital Limited | Real estate | 2005 |
| Perfect Bounce Ltd | Arts & recreation | 2013 |
| Performance Matters (N.I.) Limited | Administrative & support | 2017 |
| Petersham Studios Ltd | Extraterritorial | 2015 |
| Petra Developments (1614) Ltd | Hospitality | 1963 |
| Petra Developments 1999 Ltd | Hospitality | 1999 |
| Petts Wood (UK) Limited | Professional & scientific | 2009 |
| PG Middleton Limited | Professional & scientific | 2015 |
| Phealthcare Limited | Information & communication | 2025 |
| Phillips Estates Limited | Real estate | 1978 |
| Phoenix Construction (NI) Ltd | Construction | 2018 |
| Phoenix Hospitality Limited | Hospitality | 2024 |
| Phoenix Wine & Spirit Stores Limited | Wholesale & retail | 1951 |
| PIE Eyed Limited | Hospitality | 2024 |
| Pierce & Pierce Strategy Consulting Limited | Professional & scientific | 2025 |
| Pilates Power Limited | Other services | 2018 |
| Pink Pomelo Limited | Hospitality | 2017 |
| Pinkalicious Season Three Limited | Information & communication | 2021 |
| Pioneer Training NI Limited | Arts & recreation | 2024 |
| Placemaker Group Limited | Real estate | 2019 |
| Platinum Group Property Holdings Limited | Real estate | 2021 |
| Playfair Topco Limited | Real estate | 2019 |
| PLS Sports Ltd | Education | 2022 |
| Pmcg Radiology Ltd | Health & social care | 2025 |
| Portland II Limited | Households | 2024 |
| Powerhouse Media Productions Limited | Information & communication | 2022 |
| Preston Property Maintenance NI Limited | Construction | 2022 |
| Priory Gastroenterology Limited | Health & social care | 2022 |
| Professional Academy of Dance NI Ltd | Education | 2020 |
| Promuco Sports Limited | Wholesale & retail | 2026 |
| Property Chance Ltd | Real estate | 2019 |
| Prospect Private Nursing Home Limited | Health & social care | 2002 |
| Psychological Pathways Training Limited | Administrative & support | 2019 |
| PTB Property Limited | Real estate | 2020 |
| Pugh Software Limited | Professional & scientific | 2023 |
| Pulse Pilates Club Ltd | Wholesale & retail | 2025 |
| Pure Irish Ltd | Wholesale & retail | 2022 |
| Purecar Ltd | Professional & scientific | 2025 |
| Purposepro Solutions Ltd | Professional & scientific | 2024 |
| Quadra Limited | Professional & scientific | 2000 |
| Qualy Data Ltd | Information & communication | 2022 |
| Quantum Internet Services Ltd | Information & communication | 2020 |
| Quantum Law Solicitors Limited | Professional & scientific | 2018 |
| Quarterlands Glamping Ltd | Hospitality | 2024 |
| Quaygate Management Company Limited | Households | 2002 |
| Queen's Square Management Company Limited | Households | 2000 |
| Queens of Archive Limited | Wholesale & retail | 2020 |
| Quell Training Ltd. | Other services | 2006 |
| R G Rental Ltd | Real estate | 2026 |
| Rachel Stuart Limited | Financial services | 2025 |
| Radius Direct Limited | Construction | 2025 |
| Radius Homes Limited | Construction | 1990 |
| Rainey & Best Holdings Limited | Financial services | 2021 |
| Ramble Enterprises Limited | Professional & scientific | 2019 |
| Ranfern Limited | Wholesale & retail | 2010 |
| Rapport Fundraising Limited | Administrative & support | 2010 |
| Rathcoole Management Company Limited | Households | 2005 |
| Rayanne House Ltd | Hospitality | 2023 |
| Rebecca Mckinney Limited | Arts & recreation | 2014 |
| Recruitment Solutions (N.I.) Limited | Administrative & support | 2016 |
| Red Brick House Group Ltd | Health & social care | 2023 |
| Red Brick House Nursery Ltd | Health & social care | 2014 |
| Red Key Engineering Ltd. | Professional & scientific | 2018 |
| Redmac Trading Ltd | Households | 2023 |
| Reel Social Group Ltd | Professional & scientific | 2025 |