| Miura Investment Ltd | Real estate | 2023 |
| MJ Chandler Holdings Ltd | Professional & scientific | 2023 |
| MJ Commercial Vehicle Repair Ltd | Manufacturing | 2015 |
| MJ Ronan Landscapes Ltd | Administrative & support | 2024 |
| MJA Facilities Ltd | Real estate | 2026 |
| MJM Property Investments Limited | Real estate | 2020 |
| MJS Property Improvements Ltd | Construction | 2019 |
| MJW Holdings Limited | Professional & scientific | 2017 |
| MK Assessors Consulting Engineers Ltd | Construction | 2026 |
| MK Car Valeting Ltd | Administrative & support | 2025 |
| MK Dani Ltd | Hospitality | 2026 |
| MK Kumon Ltd | Education | 2023 |
| MK Vauxhall Spares Ltd | Wholesale & retail | 2026 |
| MK61 Ltd | Administrative & support | 2014 |
| MKL Shipping Ltd | Transport & logistics | 2024 |
| Mksorin Limited | Administrative & support | 2026 |
| Mlkk Properties Ltd | Real estate | 2024 |
| MLM Estimating Limited | Professional & scientific | 2007 |
| MLM Innovation Limited | Information & communication | 2025 |
| MM Project Solutions Ltd | Construction | 2024 |
| MME Financials Ltd | Professional & scientific | 2025 |
| MML Recovery & Transport Service Ltd | Wholesale & retail | 2019 |
| Mmmm Property Investments Limited | Real estate | 2018 |
| Mmmm Property Partnership Ltd | Real estate | 2024 |
| MND Dental Clinic Ltd | Health & social care | 2015 |
| Mniam Mniam Dunstable Ltd | Hospitality | 2020 |
| MNK Maintenance Limited | Real estate | 2020 |
| MNK Strattons Limited | Real estate | 2018 |
| Mnk&Co Limited | Construction | 2022 |
| Mnrb Holdings Ltd | Real estate | 2024 |
| Mobile Car Wash Ltd | Other services | 2015 |
| Mobile Phones X Ltd | Wholesale & retail | 2025 |
| Moda Salon Interiors Limited | Wholesale & retail | 2008 |
| Modern Day Rockstar Ltd | Wholesale & retail | 2025 |
| Modesty Financial Consultants Ltd | Financial services | 2019 |
| Modesty Property Consultants Ltd | Real estate | 2019 |
| Modibodi UK Ltd | Wholesale & retail | 2018 |
| Mogit Limited | Professional & scientific | 2019 |
| Momento Media Ltd | Information & communication | 2017 |
| Momentum-Analytics.Io Limited | Information & communication | 2019 |
| Mommy's Cleaning Services Limited | Wholesale & retail | 2024 |
| Mona Family Care Ltd | Health & social care | 2026 |
| Monaghan Media Limited | Wholesale & retail | 2017 |
| Monarch Peterborough Limited | Real estate | 2012 |
| Monarch Peterborough Property Management Limited | Real estate | 2018 |
| Monday Monday UK Limited | Professional & scientific | 2022 |
| Money Mind Ltd | Professional & scientific | 2026 |
| Monsam Ltd | Hospitality | 2026 |
| Monster Clearance Wholesale Ltd | Wholesale & retail | 2024 |
| Montague Spice Limited | Hospitality | 2019 |
| Montracon Tasker Limited | Professional & scientific | 1891 |
| Moodeys Limited | Information & communication | 2006 |
| Moon Fort Limited | Hospitality | 2023 |
| Moor Scenery Ltd | Information & communication | 2022 |
| Moore Global Investments Ltd | Real estate | 2019 |
| Moore Global Ltd | Administrative & support | 2018 |
| Moore's Healthcare Ltd | Health & social care | 2015 |
| Moorehouse Ltd | Education | 2024 |
| Mooshimity Ltd | Wholesale & retail | 2020 |
| Moraandcocollective Limited | Hospitality | 2025 |
| Moraglis Sports Cars Limited | Manufacturing | 2024 |
| Morano Imp-Export Limited | Households | 2025 |
| Morcroft Limited | Real estate | 2024 |
| More Than Board Games Community Interest Company | Wholesale & retail | 2025 |
| Moreal Property Developments Ltd | Real estate | 2026 |
| Moreno Services Limited | Transport & logistics | 2020 |
| Mortgage Beyond Ltd | Financial services | 2023 |
| Mortimer Design & Build Limited | Construction | 2024 |
| Mortimer Interiors Limited | Professional & scientific | 2024 |
| Moser Clinical Services Limited | Professional & scientific | 2021 |
| Moss Products ( Holdings ) Ltd | Financial services | 2021 |
| Moss Products Plastics Limited | Manufacturing | 1985 |
| Mostynfba Ltd | Wholesale & retail | 2025 |
| Motech Services Limited | Information & communication | 2025 |
| Mother Hubbard's Foods Ltd | Hospitality | 2026 |
| Mothern Properties Limited | Real estate | 2025 |
| Mothern Solutions Ltd | Information & communication | 2019 |
| Motion Collective Ltd | Professional & scientific | 2026 |
| Motion Rigging Limited | Construction | 2025 |
| Moto Kris Ltd | Wholesale & retail | 2017 |
| Motor Protect Limited | Administrative & support | 2026 |
| Motorcycle Trader Ltd | Wholesale & retail | 2024 |
| Mounili Ltd | Wholesale & retail | 2025 |
| Mount Lighting Holdings Limited | Professional & scientific | 2021 |
| Mount Lighting Limited | Manufacturing | 2013 |
| Mouseshopuk Limited | Wholesale & retail | 2022 |
| Movari Consulting Limited | Information & communication | 2025 |
| Move US Today Limited | Transport & logistics | 2023 |
| Movick Car Sales and Repairs Ltd | Wholesale & retail | 2024 |
| Movick Ltd | Real estate | 2020 |
| MP & Transport Ltd | Transport & logistics | 2024 |
| MP Trade House Limited | Administrative & support | 2025 |
| MPC Transport Ltd | Transport & logistics | 2018 |
| MPD Building Services Ltd | Construction | 2019 |
| MPD Freight Services Ltd | Transport & logistics | 2019 |
| MPL Electrical & SON Limited | Construction | 2019 |
| MR K Building Ltd | Construction | 2023 |
| MR Spice Valley Limited | Hospitality | 2024 |
| MR Truck Ltd | Transport & logistics | 2012 |
| Mrer Limited | Construction | 2006 |