| Q3 Exhibitions Limited | Administrative & support | 2018 |
| QAP Consulting Ltd | Professional & scientific | 2009 |
| QE Solutions Limited | Information & communication | 2024 |
| QED Events Limited | Administrative & support | 2013 |
| QEY Ltd | Wholesale & retail | 2024 |
| Qualis Healthcare IT Ltd | Information & communication | 2020 |
| Quantek Limited | Real estate | 1996 |
| Quantumpsychology Limited | Health & social care | 2025 |
| Quarry Road Management Limited | Real estate | 2003 |
| Quarters Estate Agents Ltd. | Real estate | 2010 |
| Quarters Investments Ltd | Real estate | 2025 |
| Quartz (High Wycombe) Management Company Limited | Households | 2005 |
| Quaternion House Limited | Professional & scientific | 2009 |
| Qube Catalyst Ltd | Information & communication | 2025 |
| Queens Park Cybersecurity Solutions Limited | Other services | 2018 |
| Queensfield Acquisitions Limited | Manufacturing | 2025 |
| Queensway Personnel Services Limited | Professional & scientific | 1990 |
| Queensway Staff Bureau Limited | Professional & scientific | 1970 |
| Quest Engineering & Development Limited | Real estate | 2002 |
| Quick CUT Refurbishments Limited | Construction | 2023 |
| Quidity Praxis Limited | Professional & scientific | 2022 |
| Quietly Confident Coaching Ltd | Administrative & support | 2023 |
| Quinn Admin Services Limited | Administrative & support | 2025 |
| Quinn Cush & Co Ltd | Professional & scientific | 2024 |
| Quinn Logistics Limited | Professional & scientific | 2025 |
| Quintrell Field Consulting Limited | Information & communication | 2023 |
| Quux Ltd | Information & communication | 2022 |
| R & F Webb Limited | Hospitality | 2018 |
| R & H (Southcourt Road) Management Company Limited | Households | 1992 |
| R & H Investments Limited | Construction | 1986 |
| R & J Quality Property Ltd | Real estate | 2024 |
| R D Leonard Ltd | Construction | 2011 |
| R E Technologies Ltd | Manufacturing | 2011 |
| R M Moore Consultancy Limited | Wholesale & retail | 2026 |
| R Malin Ltd | Financial services | 2018 |
| R Purkiss Services Ltd | Professional & scientific | 2024 |
| R S Stag Limited | Construction | 2012 |
| R Tiles & Interior Building Limited | Construction | 2023 |
| R Wilson Carpentry Limited | Manufacturing | 2025 |
| R&A Ventures (LDN) Ltd | Manufacturing | 2026 |
| R&D Agri Services Ltd | Agriculture & fishing | 2019 |
| R&E Enterprises Ltd | Wholesale & retail | 2025 |
| R&L Furniture London Limited | Professional & scientific | 2023 |
| R. G. Allen Limited | Real estate | 1993 |
| R.G. Contracts (Hampton) Limited | Construction | 2005 |
| R6AYM Ltd | Information & communication | 2023 |
| RAB & Amigo Ltd | Construction | 2020 |
| Rabournmead (Hillingdon) Management Company Limited | Households | 1988 |
| Radford EZY NET Limited | Manufacturing | 1994 |
| Radford Household Properties Limited | Hospitality | 2017 |
| Radio Dog Ltd | Information & communication | 2020 |
| Rafajos Developments Ltd | Real estate | 2024 |
| Raffaella Hair Studio Limited | Other services | 2012 |
| Raft Programme CIC | Education | 2025 |
| Ragnar-Rock Ltd | Transport & logistics | 2020 |
| Rahh Consulting Limited | Professional & scientific | 2025 |
| Raise Composition Ltd | Information & communication | 1999 |
| RAJ Stores Ltd | Wholesale & retail | 2016 |
| Raka Properties Ltd | Real estate | 2023 |
| RAM Online Limited | Wholesale & retail | 2016 |
| Rammamere House Limited | Other services | 2017 |
| Randall Herc Construction Ltd | Construction | 2024 |
| Rapid 3D (UK) Limited | Professional & scientific | 2011 |
| Ravinder Crone Ltd | Professional & scientific | 2015 |
| RAW Mechanical Services Ltd | Construction | 2019 |
| RAY House (Cressington Place) Management Company Limited | Households | 1967 |
| RAY Law Agencies Limited | Professional & scientific | 2012 |
| RBK Holdings Ltd | Financial services | 2025 |
| RC Solution Services Limited | Wholesale & retail | 2025 |
| RCH IT Consultants Limited | Information & communication | 2018 |
| Rconnor Limited | Professional & scientific | 2024 |
| Realkleen Limited | Manufacturing | 2020 |
| Ream Court RTM Company Limited | Households | 2023 |
| Reasons to BE Cheerful LB Ltd | Arts & recreation | 2019 |
| Rebe Design Limited | Professional & scientific | 2026 |
| Reborn Plumbing and Heating Ltd | Construction | 2026 |
| Reborncars Ltd | Wholesale & retail | 2025 |
| Recruit Gold Class LLP | | 2018 |
| Red Kite Technology Solutions Limited | Information & communication | 2022 |
| Red Lion PUB Lighten Buzzards Limited | Hospitality | 2025 |
| Red Octopus Transformation Limited | Professional & scientific | 2017 |
| Red OR Black 100 Limited | Wholesale & retail | 2014 |
| Red Rascal Creative Ltd | Arts & recreation | 2008 |
| Red Services (MK) Limited | Manufacturing | 2015 |
| Red Services (UK) Ltd | Construction | 2011 |
| Red Swift Property Services Ltd | Real estate | 2022 |
| Red Tulip Limited | Professional & scientific | 2002 |
| Red Velvet Music Group Limited | Information & communication | 2013 |
| Redcat Products Limited | Wholesale & retail | 2015 |
| Redlightworks Limited | Health & social care | 2026 |
| Redmond Consulting Limited | Professional & scientific | 2021 |
| Redrag Aircraft Certifications Limited | Professional & scientific | 2019 |
| Redroofs Bath Road Taplow RTE Company Limited | Administrative & support | 2004 |
| Redwood Fire Safety Ltd | Public administration | 2025 |
| Reflect Training and Consultancy Ltd | Professional & scientific | 2020 |
| Refrays Limited | Real estate | 2026 |
| Regalscroll Limited | Hospitality | 1983 |
| Regent Court Residents Company Limited | Households | 1987 |
| Regent's Content Ltd | Manufacturing | 2024 |
| Reggy Electrical Ltd | Construction | 2015 |