| Qualicrcvc Ltd | Construction | 2025 |
| Qualified Care Residential Services Ltd | Health & social care | 2019 |
| Qualigrad International Limited | Information & communication | 2025 |
| Qualiteam Prod. Ltd | Manufacturing | 2020 |
| Qualitec Projects Limited | Construction | 2022 |
| Qualitech Integrated Services Limited | Information & communication | 2012 |
| Quality Assured Facility Services Limited | Administrative & support | 1999 |
| Quality Carpets Direct Limited | Wholesale & retail | 2008 |
| Quality Courier Services Limited | Transport & logistics | 2017 |
| Quality Design and Construction Limited | Construction | 2019 |
| Quality Floorcare Limited | Administrative & support | 1993 |
| Quality Imports & Exports Limited | Wholesale & retail | 2018 |
| Quality IT Limited | Information & communication | 2013 |
| Quality IT Network Solutions Limited | Information & communication | 2024 |
| Quality Landscapes Ltd | Administrative & support | 2017 |
| Quality Motorhouse Group Limited | Wholesale & retail | 2016 |
| Quality Paving Services Limited | Administrative & support | 2006 |
| Quality Prepared Limited | Wholesale & retail | 2018 |
| Quality Staffing Care Ltd | Administrative & support | 2025 |
| Quality, Inspection & Integrity Services Limited | Construction | 2019 |
| QUALITYWEAR62 Ltd | Wholesale & retail | 2024 |
| Quandary Productions Ltd | Information & communication | 2018 |
| Quant Lynx Ltd | Information & communication | 2020 |
| Quantage Ltd | Administrative & support | 2017 |
| Quantale Ltd | Wholesale & retail | 2025 |
| Quantam Limited | Financial services | 2021 |
| Quantapay Limited | Information & communication | 2025 |
| Quantapp Ltd | Information & communication | 2015 |
| Quantarnet Limited | Manufacturing | 2026 |
| Quantea Site 2 Ltd | Wholesale & retail | 2019 |
| Quantech Trading Technologies Ltd | Information & communication | 2021 |
| Quanti Consulting Ltd | Professional & scientific | 2022 |
| Quanti Meta Limited | Professional & scientific | 2025 |
| Quantra International Ltd | Information & communication | 2025 |
| Quantum Acquisitions Limited | Information & communication | 2016 |
| Quantum Actuarial LLP | | 2007 |
| Quantum Advisory Limited | Financial services | 2006 |
| Quantum Business Global | Information & communication | 2019 |
| Quantum Cafe Ltd | Hospitality | 2023 |
| Quantum Cloud Computing Limited | Information & communication | 2024 |
| Quantum Coffee Roasters Ltd | Manufacturing | 2015 |
| Quantum Commercial Ltd | Professional & scientific | 2020 |
| Quantum Core Consulting Limited | Information & communication | 2016 |
| Quantum Data Ltd | Information & communication | 2019 |
| Quantum Design Projects Limited | Construction | 2020 |
| Quantum Electrical Ltd | Construction | 2025 |
| Quantum Fitness Limited | Arts & recreation | 2017 |
| Quantum Hire Ltd | Administrative & support | 2020 |
| Quantum Innovix Ltd | Wholesale & retail | 2026 |
| Quantum Investment Group Ltd | Financial services | 2019 |
| Quantum London Limited | Wholesale & retail | 2019 |
| Quantum Marketing Academy Ltd | Information & communication | 2025 |
| Quantum MIX Ltd | Wholesale & retail | 2023 |
| Quantum Nexus Danismanlik Ltd | Information & communication | 2025 |
| Quantum Project Management Ltd | Construction | 2018 |
| Quantum Shift Exploration Ltd | Information & communication | 2025 |
| Quantum Whale Ltd | Financial services | 2026 |
| Quantumcls Limited | Professional & scientific | 2018 |
| Quantumcls Property Ltd | Real estate | 2022 |
| Quantumhive Ltd | Wholesale & retail | 2025 |
| Quantumtech IT Solutions Ltd | Information & communication | 2025 |
| Quantumtech Ventures Ltd | Financial services | 2023 |
| Quantx Capital Ltd | Financial services | 2024 |
| Quantza Ltd | Wholesale & retail | 2025 |
| Quarry & Castle Limited | Administrative & support | 2017 |
| Quarry Hill Lodge Apartments Ltd | Real estate | 2022 |
| Quarterdeck Realty Ltd | Real estate | 2012 |
| Quarthome Property Management Limited | Professional & scientific | 1984 |
| Quartoscope Media Ltd | Information & communication | 2017 |
| Quartz Mortgage Advice Limited | Financial services | 2016 |
| Quartz Plumbing and Heating Ltd | Construction | 2022 |
| Quasar Assets Management Ltd | Financial services | 2024 |
| Quasistate Business Group PC | | 2019 |
| Quasr Solutions Ltd | Administrative & support | 2025 |
| Quasys Ltd | Information & communication | 2009 |
| Quatro Ltd | Wholesale & retail | 2025 |
| Quattro Developments Limited | Construction | 2016 |
| Quattro International Ltd | Professional & scientific | 2025 |
| Quattro Payroll Ltd | Professional & scientific | 2019 |
| Quattro Services Ltd | Administrative & support | 2020 |
| Quavar Ltd | Real estate | 2016 |
| Quay Games Ltd | Information & communication | 2024 |
| Quay Street Cantina Ltd | Hospitality | 2019 |
| Quaydrum Solutions Limited | Professional & scientific | 2013 |
| Quayside Cardiff Lettings Limited | Real estate | 2006 |
| Quayside Consulting Ltd | Professional & scientific | 2026 |
| Quayside Management Company (Wales) Limited | Households | 2010 |
| Quazmi Recruits Ltd | Administrative & support | 2020 |
| Qube-It Ltd | Manufacturing | 2015 |
| Qubic Home Investments Ltd | Construction | 2016 |
| Queen Anne Square Management Company Limited | Households | 1986 |
| Queenley Ltd | Other services | 2019 |
| Queens Fish Bar Ltd | Hospitality | 2018 |
| Quen Store Ltd | Wholesale & retail | 2025 |
| Quena Stores Ltd | Wholesale & retail | 2025 |
| Quer Limited | Wholesale & retail | 2025 |
| Quest IT Recruitment Limited | Administrative & support | 2016 |
| Quest Recruiting Ltd | Administrative & support | 2023 |
| Quest-Mart Limited | Wholesale & retail | 2014 |
| QUEST22 LLP | | 2025 |