| Optimus Management Consultancy Ltd | Professional & scientific | 2009 |
| Opus Automotive Cars Ltd | Wholesale & retail | 2024 |
| Opus Automotive Ltd | Wholesale & retail | 2019 |
| Opus Point Limited | Households | 2006 |
| Opus Point Management Company Limited | Real estate | 2003 |
| Orange Bikes Ltd | Manufacturing | 2006 |
| Orange Wolf Consulting Ltd | Professional & scientific | 2019 |
| Orca Services Limited | Professional & scientific | 2009 |
| Orchard Leigh Management Company Limited | Households | 2023 |
| Orcharditconsultancy Ltd | Information & communication | 2023 |
| Orchards River (Consultants) Ltd | Professional & scientific | 2023 |
| Organic Gains Ltd | Wholesale & retail | 2023 |
| Orient Hall Management Consultancy Ltd | Professional & scientific | 2011 |
| Origano Pizza and Grill Ltd | Hospitality | 2018 |
| Orion Interiors Ltd | Administrative & support | 2016 |
| Orsorg Ltd | Information & communication | 2023 |
| Orthoaligners Ltd | Health & social care | 2015 |
| Orthomations Limited | Information & communication | 2025 |
| ORX Consultants Limited | Professional & scientific | 2025 |
| OS Pension Trustees Limited | Professional & scientific | 2019 |
| OSC Developments Ltd | Construction | 2019 |
| Osca Foundation Ltd | Arts & recreation | 2010 |
| Oscar Grace Mortgages Limited | Financial services | 2020 |
| Oscar Wilde Ltd | Hospitality | 2018 |
| Osprey Couriers Ltd | Transport & logistics | 2026 |
| Ostra Douro Limited | Wholesale & retail | 2025 |
| OT 4 Kids With DCD Ltd | Health & social care | 2014 |
| Otis Development Ltd | Information & communication | 2024 |
| OTJ Plastering Services Ltd | Construction | 2019 |
| Ottersmart Limited | Manufacturing | 2016 |
| OUR Pharma Failsworth Ltd | Wholesale & retail | 2019 |
| OUR Pharma Hopwood Ltd | Wholesale & retail | 2019 |
| Outdo Airports Limited | Professional & scientific | 2006 |
| Outdo Media Group Limited | Professional & scientific | 2010 |
| Outdo Media Limited | Administrative & support | 1992 |
| Outdo Transport Limited | Professional & scientific | 2006 |
| Outdoor Living 365 Limited | Wholesale & retail | 2017 |
| Outerbeauty Ltd | Other services | 2025 |
| Outperform Coaching Limited | Education | 2024 |
| Ovenden Arlfc CIC | Education | 2026 |
| Ovenden Healthcare Ltd | Health & social care | 2015 |
| Ovenden Mini Market Ltd | Wholesale & retail | 2023 |
| Ovenden OFF Licence Ltd | Wholesale & retail | 2010 |
| Ovenden Sports and Community Arena CIC | Arts & recreation | 2010 |
| Overgate Hospice | Health & social care | 1980 |
| Overgreen Joinery Ltd | Manufacturing | 2011 |
| Overland Campers Limited | Administrative & support | 2016 |
| Overland Supplies Ltd | Wholesale & retail | 2021 |
| Overseas Pakistanis British Hub Ltd | Other services | 2023 |
| Ovopod Ltd | Construction | 2017 |
| Oxford Street Cafe Limited | Hospitality | 2022 |
| Oxley Investments Limited | Real estate | 2025 |
| Oxney Eyre Ltd | Wholesale & retail | 2025 |
| Oyler & Co. Limited | | 1948 |
| Oyster Ceilings Ltd | Construction | 2009 |
| OZ Customs Limited | Wholesale & retail | 2017 |
| OZ Joinery Solutions Limited | Construction | 2021 |
| Ozaish Limited | Wholesale & retail | 2025 |
| Ozdemirci Property Ltd | Households | 2025 |
| Ozsel Ltd | Hospitality | 2022 |
| O’Hara Brothers Property Ltd | Real estate | 2025 |
| P & Backgammon Ltd | Hospitality | 2025 |
| P & G S (Yorkshire) Limited | Construction | 2024 |
| P & W Plumbing and Tiling Ltd | Construction | 2022 |
| P a Robinson Limited | Manufacturing | 2003 |
| P and L Nurseries Limited | Education | 2013 |
| P B B Properties Limited | Construction | 2010 |
| P C B Group Limited | Information & communication | 1993 |
| P C Lifting Services Ltd | Manufacturing | 2003 |
| P Cooper Plumbing & GAS Services Ltd | Wholesale & retail | 2025 |
| P Cribbin Refrigeration Limited | Manufacturing | 2011 |
| P J Cheffy Limited | Hospitality | 2025 |
| P S B Systems Limited | Construction | 1997 |
| P Smith Flooring Limited | Administrative & support | 2017 |
| P&F Fabrications Ltd | Construction | 2023 |
| P&G Properties (HX) Limited | Real estate | 2026 |
| P&L Gilroy Property Ltd | Real estate | 2021 |
| P&L Housing Limited | Construction | 2002 |
| P&S Takeaway Limited | Hospitality | 2020 |
| P. Ainley Joinery Ltd | Construction | 2020 |
| P. L. Controls Limited | Other services | 1996 |
| P. P. Building & Roofing Ltd | Construction | 2014 |
| P. W. Greenhalgh Holdings Limited | Real estate | 2005 |
| P. Wilkinson (Bakers) Limited | Manufacturing | 1950 |
| P.R.B. Technologies Ltd | Professional & scientific | 1997 |
| P2I Trading Limited | Wholesale & retail | 2009 |
| PA Delivery Ltd | Transport & logistics | 2020 |
| Pacfor Limited | Wholesale & retail | 2014 |
| Packing Technology Limited | Wholesale & retail | 2011 |
| PAD4L Ltd | Manufacturing | 2026 |
| Padan Street 1974 Limited | Extraterritorial | 2014 |
| Paddock Lane Investment Limited | Real estate | 2025 |
| Paddycaster Ltd | Hospitality | 2022 |
| Paige Education Ltd | Education | 2025 |
| Palace Clubs Ltd | Education | 2025 |
| Palace Gym Ltd | Arts & recreation | 2026 |
| Paladin Marketing Ltd | Professional & scientific | 2020 |
| Pale Pink Properties Ltd | Construction | 2025 |
| Pall Investment (Holdings) Ltd | Financial services | 2025 |
| Palladam Ltd | Real estate | 2021 |