| Mudhaus Ltd | Wholesale & retail | 2024 |
| Mudindo Ltd | Health & social care | 2022 |
| Mudiru Investment Ltd | Hospitality | 2026 |
| Mudiwa Healthcare Limited | Health & social care | 2022 |
| Mudlarks Investments Ltd | Administrative & support | 2020 |
| Mudra Associates Ltd | Information & communication | 2017 |
| Muflic & Partners Limited | Professional & scientific | 2016 |
| Muflic Notaries Limited | Professional & scientific | 2024 |
| Mughal Construction A1 Limited | Construction | 2024 |
| Mughal Indian Ltd | Hospitality | 2025 |
| Mughal Tandoori (Notts) Ltd | Hospitality | 2023 |
| Mughalexclusive Ltd | Wholesale & retail | 2026 |
| Mugo UK Limited | Wholesale & retail | 2025 |
| Muhammad Ahmad Rana Ltd | Wholesale & retail | 2025 |
| Muhammad Ammar Ltd | Wholesale & retail | 2025 |
| Muhammad Muddassir ALI Ltd | Manufacturing | 2025 |
| Muhammad Superstore Limited | Wholesale & retail | 2026 |
| Mujtaba Qayum Ltd | Wholesale & retail | 2012 |
| Mukhtar Global Horizon Ltd | Wholesale & retail | 2026 |
| Mukky Duck Events Ltd | Arts & recreation | 2011 |
| MUKS6 Ltd | Public administration | 2019 |
| Mukuyu Limited | Manufacturing | 2026 |
| Mulberry Bush Nursery Mansfield Ltd | Real estate | 2013 |
| Mulberry Lane Estates Limited | Households | 2025 |
| Mulberry Media Ltd | Information & communication | 2018 |
| Mulberry World Gardens & Landscaping Ltd | Administrative & support | 2018 |
| Muldoon Holdings (Loughborough) Limited | Real estate | 2019 |
| Muldoon Properties Limited | Real estate | 2024 |
| Mulitob Limited | Health & social care | 2025 |
| Mullacott Country Park Limited | Hospitality | 2019 |
| Mulligan and Macmillan Properties Limited | Real estate | 2020 |
| Multan Group Ltd | Education | 2025 |
| Multi ABC Limited | Education | 2015 |
| Multi Axle Limited | Transport & logistics | 2009 |
| Multi Consultant Ltd | Professional & scientific | 2015 |
| Multi Packaging Solutions Acquisitions 1 Limited | Professional & scientific | 1999 |
| Multi Packaging Solutions Acquisitions 2 Limited | Financial services | 1998 |
| Multi Packaging Solutions Asia Holdings Limited | Financial services | 2010 |
| Multi Packaging Solutions Bristol Limited | Manufacturing | 1975 |
| Multi Packaging Solutions Featherstone Limited | Manufacturing | 2009 |
| Multi Packaging Solutions GB Limited | Financial services | 1991 |
| Multi Packaging Solutions Global Holdings Limited | Financial services | 2013 |
| Multi Packaging Solutions Leasing Limited | Financial services | 2013 |
| Multi Packaging Solutions Littlehampton Limited | Manufacturing | 2009 |
| Multicast Audio Limited | Information & communication | 2014 |
| Multicast Vision Limited | Information & communication | 2022 |
| Multidwell Limited | Real estate | 2025 |
| Multihands Ltd | Information & communication | 2021 |
| Multimarketing Ltd | Wholesale & retail | 2025 |
| Multiops Limited | Wholesale & retail | 2011 |
| Multipie Ltd | Information & communication | 2011 |
| Multiple Times Better Limited | Health & social care | 2005 |
| Multisign Limited | Manufacturing | 2006 |
| Multistrip (UK) Limited | Manufacturing | 2013 |
| Multiverse (Bidco) Limited | Administrative & support | 2024 |
| Multiverse (Midco 1) Limited | Administrative & support | 2024 |
| Multiverse (Midco 2) Limited | Administrative & support | 2024 |
| Multiverse (Topco) Limited | Administrative & support | 2024 |
| Multiwayasset Ltd | Real estate | 2022 |
| MUM and ME Properties Limited | Real estate | 2025 |
| Mum's Helping Hands Limited | Other services | 2009 |
| Mumbai Spice Ltd | Hospitality | 2026 |
| Mumeen Limited | Information & communication | 2024 |
| Mummy's Care Ltd | Health & social care | 2023 |
| Mums Essentials Limited | Manufacturing | 2014 |
| Mumzy Ltd | Manufacturing | 2019 |
| Munatsi Logistics Ltd | Transport & logistics | 2012 |
| Munch Munch Ltd | Hospitality | 2022 |
| Munch Shack Ltd | Hospitality | 2026 |
| Munchville Ltd | Hospitality | 2025 |
| Mundell Cleaning Limited | Administrative & support | 2021 |
| Mundella Antiques Ltd | Wholesale & retail | 2020 |
| Mundia's Collections Ltd | Wholesale & retail | 2018 |
| Mundy's Services Limited | Households | 1998 |
| Municipal Maverick Limited | Professional & scientific | 2023 |
| Munjasmin Ltd | Hospitality | 2025 |
| Munkbridge Homes Limited | Construction | 2015 |
| Munks Homes Limited | Real estate | 2022 |
| Munn Cars Ltd | Wholesale & retail | 2025 |
| Mur-Ham Burger Ltd | Hospitality | 2025 |
| Muraad Retail Limited | Wholesale & retail | 2023 |
| Muraad Retail Tiktok Limited | Wholesale & retail | 2025 |
| Muradstudios Ltd | Professional & scientific | 2025 |
| Murat Food Centre Ltd | Wholesale & retail | 2013 |
| Murchie Property Management Company Ltd | Real estate | 2020 |
| Murden Homes Ltd | Real estate | 2017 |
| Murden Properties Ltd | Extraterritorial | 2020 |
| Murden Property Co Ltd | Real estate | 2022 |
| Murdoch Barry Site Management Services Limited | Construction | 2018 |
| Muresan FLW Limited | Other services | 2018 |
| Murk Hair Experts Ltd | Other services | 2024 |
| Murphy & SON International Limited | Professional & scientific | 2017 |
| Murphy & SON Limited | Manufacturing | 1909 |
| Murphy Collective Limited | Administrative & support | 2025 |
| Murphy Engineering Services Limited | Construction | 2008 |
| Murray & Willis Holdings Limited | Financial services | 2025 |
| Murray Biosciences Ltd | Professional & scientific | 2012 |
| Murray Rail Limited | Construction | 2013 |
| Murrays Funeral Directors Limited | Extraterritorial | 2005 |
| Musa Edits Ltd | Information & communication | 2022 |