| MBS Care Solutions Ltd | Health & social care | 2025 |
| Mbsbh Construction Ltd | Construction | 2021 |
| Mbsc Consultancy Ltd | Professional & scientific | 2019 |
| Mbsi Services Limited | Information & communication | 2018 |
| MBT Project Controls Ltd | Administrative & support | 2022 |
| MBW Consulting Limited | Administrative & support | 2016 |
| MBW Holdings Ltd | Financial services | 2025 |
| MC CAD Limited | Administrative & support | 2014 |
| MC Data Analytics Ltd | Information & communication | 2025 |
| MC Grail Associates Limited | Public administration | 2007 |
| MC Housing Solutions Limited | Real estate | 2019 |
| MC Hymers Engineering Limited | Administrative & support | 2012 |
| MC Perforated Limited | Wholesale & retail | 2012 |
| MC Project Management Limited | Administrative & support | 2007 |
| MC Strat Limited | Information & communication | 2014 |
| Mc-It-Tech Limited | Information & communication | 2017 |
| MC2 Stratedy T/A Radicl Ltd | Professional & scientific | 2019 |
| MC3 Events & Travel Ltd | Other services | 2024 |
| MCA Professional Limited | Professional & scientific | 2024 |
| Mcalpine Anchor Enterprises Ltd | Administrative & support | 2020 |
| MCC Fabrications Limited | Manufacturing | 2001 |
| MCC Steelworks Limited | Manufacturing | 2020 |
| Mccafferty Piping Consultancy Limited | Professional & scientific | 2019 |
| Mccaig Art Ltd | Wholesale & retail | 2025 |
| Mccarron Manufacturing Associates Ltd | Administrative & support | 2007 |
| Mccarthy Assets Ltd | Professional & scientific | 2020 |
| Mccarthy DC Services Ltd | Administrative & support | 2025 |
| Mccarthy Recruitment Holdings Limited | Professional & scientific | 2020 |
| Mccarthy Recruitment Limited | Administrative & support | 2004 |
| Mccormick Properties (NW) Limited | Real estate | 2025 |
| Mccoys Warrington Limited | Hospitality | 2026 |
| MCD Northwest Ltd | Construction | 2026 |
| Mcdc Services Limited | Other services | 2018 |
| Mcdonald Education Limited | Education | 2024 |
| Mcdonald Engineering Consultancy Limited | Professional & scientific | 2016 |
| Mcduff Commissioning Limited | Administrative & support | 2025 |
| MCF Investments Limited | Real estate | 2024 |
| MCG Change Ltd | Information & communication | 2013 |
| MCG Engineering Services Limited | Professional & scientific | 2017 |
| Mcgee Noise & Vibration Limited | Administrative & support | 2025 |
| Mcgonigal Engineering Solutions Ltd | Professional & scientific | 2020 |
| Mcgowan Change Consultancy Ltd | Administrative & support | 2026 |
| Mcguinness Estates Limited | Real estate | 2024 |
| Mcguire's NW Ltd | Extraterritorial | 2023 |
| Mcguirk Management Solutions Ltd | Professional & scientific | 2015 |
| MCH UK Engineering Limited | Administrative & support | 2026 |
| Mchugh Consultancy Ltd | Administrative & support | 2021 |
| Mciver Wealth Management Ltd | Financial services | 2019 |
| MCJ Properties (MCR) Limited | Real estate | 2026 |
| Mckay Construction (Shropshire) Limited | Construction | 2010 |
| Mckenna Design Solutions Limited | Administrative & support | 2012 |
| Mckenzie Consulting Partners Limited | Information & communication | 2015 |
| Mckenzie James Engineering Ltd | Administrative & support | 2021 |
| Mckenzie Jude LLP | | 2007 |
| Mckenzie Urban Renew Ltd | Real estate | 2026 |
| Mckfly Aviation Limited | Professional & scientific | 2010 |
| Mckinlay Consultants Limited | Administrative & support | 2011 |
| Mckinney Electrical Limited | Administrative & support | 2014 |
| Mckinnon Actuarial Limited | Professional & scientific | 2023 |
| Mckinnon Medical Limited | Health & social care | 1993 |
| Mcknight Ltd | Information & communication | 2024 |
| Mckraff Ltd | Information & communication | 2023 |
| MCL CON Limited | Administrative & support | 2014 |
| MCL Digital Media Solutions Ltd | Professional & scientific | 2016 |
| MCL Property Ventures Limited | Real estate | 2024 |
| Mclardie Consultancy Limited | Construction | 2019 |
| Mclaren Piping Design Limited | Administrative & support | 2014 |
| Mclaughlin IT Contracting Ltd | Administrative & support | 2022 |
| Mclennan Building Services Limited | Administrative & support | 2009 |
| Mclennan Compliance Limited | Extraterritorial | 2015 |
| Mclennan Group Ltd | Financial services | 2015 |
| Mclennan Investments Limited | Extraterritorial | 2015 |
| Mclennan Mechanical Limited | Extraterritorial | 2015 |
| Mcloughlin Marketing Consultancy Ltd | Professional & scientific | 2022 |
| Mcmb Property Company Ltd | Real estate | 2020 |
| Mcmeeking Professional Services Limited | Professional & scientific | 2026 |
| Mcnulty Project Management Ltd | Information & communication | 2018 |
| MCP Consulting Solutions Limited | Administrative & support | 2025 |
| MCP Design Consultants Ltd | Professional & scientific | 2012 |
| MCQ Technologies Limited | Information & communication | 2024 |
| Mcqueen Legal Limited | Professional & scientific | 2021 |
| MCR Group Holdings Ltd | Financial services | 2022 |
| Mcrossan Consulting Ltd | Administrative & support | 2026 |
| MCS Charitable Foundation | Education | 2016 |
| MCS IT Limited | Other services | 2018 |
| MCW Construction Solutions Limited | Construction | 2024 |
| MD Building Projects Limited | Administrative & support | 2018 |
| MD Expo Logistics Ltd | Manufacturing | 2019 |
| MD Plumbing & Bespoke Bathrooms Ltd | Construction | 2023 |
| MD UK Inspections Limited | Administrative & support | 2011 |
| Mdata Consulting Limited | Wholesale & retail | 2011 |
| MDC Electrical Design Limited | Administrative & support | 2013 |
| MDC Ventures Limited | Information & communication | 2020 |
| MDG Property Solutions Limited | Real estate | 2025 |
| Mdl.Cc Ltd | Professional & scientific | 2023 |
| Mdlmkr Limited | Professional & scientific | 2021 |
| MDM Automation Limited | Information & communication | 2021 |
| MDM Consultancy Limited | Administrative & support | 2026 |
| MDM Design Ltd | Professional & scientific | 2016 |
| MDM Financial Planning Ltd | Financial services | 2025 |