| MG Building Service Ltd | Construction | 2014 |
| MG Education Holdings Ltd | Education | 2026 |
| MG Elite Construction Ltd | Construction | 2026 |
| MG Joinery Bespoke Furniture Ltd | Manufacturing | 2023 |
| MG Media Consultancy Limited | Administrative & support | 2016 |
| MG Support Services Limited | Education | 2023 |
| MG Tech Services Limited | Information & communication | 2014 |
| MGA Contracting Ltd | Construction | 2026 |
| MGM Pro Solutions Ltd | Construction | 2017 |
| MGS Multi Trade Ltd | Wholesale & retail | 2020 |
| Mgss Consultants Ltd | Education | 2024 |
| Mhads Ltd Ltd | Wholesale & retail | 2020 |
| MHZ Solutions Limited | Information & communication | 2018 |
| Miall Build Ltd | Construction | 2023 |
| Miaroby Private Hire Ltd | Transport & logistics | 2023 |
| Micaiah Services Ltd | Manufacturing | 2020 |
| Michael Evans and Company Limited | Professional & scientific | 1999 |
| Michael Mcgrath Management Services Limited | Professional & scientific | 2003 |
| Michael Potts Limited | Health & social care | 2010 |
| Micheal James Limited | Construction | 2026 |
| Michels & Taylor Op-Co B Limited | Hospitality | 2021 |
| Michels & Taylor Op-Co E Limited | Hospitality | 2021 |
| Michels & Taylor Op-Co S Limited | Hospitality | 2021 |
| Micrah Healthcare Ltd | Administrative & support | 2023 |
| Microlin Cooper Ltd | Wholesale & retail | 1998 |
| Midas Gold & Diamonds Ltd | Manufacturing | 2021 |
| Midas Properties & Investments Ltd | Real estate | 2021 |
| Midas Property Trading Ltd | Real estate | 2021 |
| Middlesex & Herts Ltd | Administrative & support | 2014 |
| Midland Roofing Contractors Limited | Professional & scientific | 2012 |
| MIG Management Limited | Households | 2025 |
| Migh Limited | Wholesale & retail | 2015 |
| Mihai Manolache Ltd | Construction | 2015 |
| Mihaila & Company Ltd | Construction | 2013 |
| MII Chii Wellbeing Ltd | Administrative & support | 2021 |
| Mijo Jewellery Limited | Other services | 2012 |
| Mikah Music Ltd. | Information & communication | 2013 |
| Mikan Finance (UK) Limited | Real estate | 2017 |
| Mike Penning Consulting Limited | Professional & scientific | 2024 |
| Milemaster Transport Ltd | Transport & logistics | 2024 |
| Miles Better Plumbing Limited | Construction | 2020 |
| Milieu Freehold Limited | Real estate | 2005 |
| Mill Farm (Residents Management Company) Limited | Households | 2016 |
| Mill Hill Inns Limited | Hospitality | 2012 |
| Mill Rythe Limited | Hospitality | 2010 |
| Milldown Residents Limited | Households | 2015 |
| Millennium 247 Taxis Ltd | Transport & logistics | 2019 |
| Miller Executive Travel Limited | Transport & logistics | 2022 |
| Millers Court (Stalybridge) Management Company Limited | Households | 2006 |
| Millers Wharf (Stalybridge) Management Company Limited | Households | 2002 |
| Millie James Limited | Professional & scientific | 2024 |
| Millimetre Perfect Ltd | Information & communication | 2023 |
| Millmania Productions Limited | Information & communication | 2012 |
| Milos Marbles Limited | Construction | 2014 |
| Milton Keynes Entertainment Company Limited | Extraterritorial | 1984 |
| Mimi's Nursery Ltd | Education | 2022 |
| MIN Delivery Ltd | Transport & logistics | 2018 |
| Mind Attic Limited | Information & communication | 2025 |
| Mind Body Heaven Ltd | Health & social care | 2024 |
| Mind Body Spirit Events Ltd | Administrative & support | 2023 |
| Mind Body Spirit Festival Ltd | Administrative & support | 2014 |
| Mind Body Spirit Limited | Extraterritorial | 2015 |
| Mind Head Publishing Limited | Information & communication | 2010 |
| Mind Makr Ltd | Information & communication | 2013 |
| Mind Motion Creation Ltd | Agriculture & fishing | 2024 |
| Mindenhurst Residents Management Company Limited | Households | 2021 |
| Mindenhurst Residents Management Company NO.1 Limited | Households | 2021 |
| Mindful Energy Ltd | Professional & scientific | 2023 |
| Mindful Recruits Ltd | Extraterritorial | 2024 |
| Minds Alike Dog Training Ltd | Professional & scientific | 2022 |
| Minha Syed Ltd | Wholesale & retail | 2020 |
| Minimal Glass Limited | Administrative & support | 2018 |
| Mining & Engineering Services Ltd | Mining & quarrying | 2026 |
| Mint (Braithwell Road) Management Company Limited | Households | 2006 |
| Miracle Christian Centre International Limited | Other services | 2003 |
| Mirafushion Ltd | Information & communication | 2025 |
| Miramar Concept Properties Limited | Real estate | 2024 |
| Mirembe Publishing Company Ltd | Wholesale & retail | 2020 |
| Misbourne Properties Ltd | Real estate | 2026 |
| Miss Sally & Company Ltd | Professional & scientific | 2023 |
| Mister Real Estate Ltd | Real estate | 2023 |
| Mister Water Softener Ltd | Water & waste | 2024 |
| Mistral Recruitment Solutions Ltd | Administrative & support | 2009 |
| Mitchell Urban Developments Limited | Real estate | 2026 |
| Mitchellbrooks Controls Limited | Professional & scientific | 2024 |
| Mitchellbrooks Limited | Real estate | 2022 |
| Mitchelle Care Ltd | Health & social care | 2018 |
| Mitouch Limited | Professional & scientific | 2024 |
| Mitres Fabrication Ltd | Manufacturing | 2024 |
| Mitrut Construction Ltd | Administrative & support | 2016 |
| MIV Interiors Ltd | Construction | 2020 |
| Miza Logistics Limited | Transport & logistics | 2018 |
| MJB Personal Assistant Limited | Administrative & support | 2017 |
| MJC Paraplanning Ltd | Financial services | 2025 |
| MJH Plastering Ltd | Construction | 2024 |
| MJL Contract Management Ltd | Construction | 2025 |
| MJM Care Limited | Health & social care | 2024 |
| MJM Media Services Limited | Information & communication | 2023 |
| MJM Retail Ltd | Wholesale & retail | 2022 |
| MK Surfaces Ltd | Extraterritorial | 2023 |