| Mightyoak Garden Services Limited | Administrative & support | 2014 |
| Migrate Technology Limited | Manufacturing | 2002 |
| Mihai Gabriel Ltd | Manufacturing | 2025 |
| Mihai Ioan Composites Ltd | Manufacturing | 2018 |
| Mihai Trihub Ltd | Manufacturing | 2023 |
| Mihail Construction Limited | Construction | 2019 |
| Mihail Vasilica Ltd | Manufacturing | 2026 |
| MII Studio Ltd | Professional & scientific | 2021 |
| Mijan Limited | Information & communication | 1984 |
| Mikail Autos UK Ltd | Wholesale & retail | 2021 |
| Mike Butler Associates Limited | Other services | 2023 |
| Mike Irvine - Flexible Resourcing Limited | Administrative & support | 2011 |
| Mike Klassen Consulting Ltd | Professional & scientific | 2024 |
| Mike Trade Ltd | Manufacturing | 2025 |
| Mike Walden Screenwriter Ltd | Professional & scientific | 2020 |
| Mikida Composites Ltd | Manufacturing | 2023 |
| MIL TRG Ltd | Education | 2024 |
| Milaino Group Trading Company Limited | Wholesale & retail | 2025 |
| Milc Ltd | Real estate | 2020 |
| Miles Academy Ltd | Arts & recreation | 2025 |
| Miles LI Ltd | Administrative & support | 2024 |
| Milestone Apartments Ltd | Real estate | 2021 |
| Milfords Software Ltd | Information & communication | 2010 |
| Militaruworksolution Ltd | Manufacturing | 2026 |
| Milksea Limited | Information & communication | 2025 |
| Mill Road Library CIC | Information & communication | 2024 |
| Mill Road Massive Limited | Arts & recreation | 2026 |
| Mill Road Mini Market Ltd | Wholesale & retail | 2026 |
| Mill Road Shawarma Ltd | Hospitality | 2026 |
| Mill Road Supermarket Ltd | Wholesale & retail | 2022 |
| Mill Road Traders CIC | Other services | 2023 |
| Mill Road Winter Fair CIC | Administrative & support | 2026 |
| Mill Taylors Ltd | Other services | 2019 |
| Mill View (Cowbit) Management Company Limited | Households | 2017 |
| Mill View (Sibsey) Management Company Limited | Households | 2022 |
| Millcam Limited | Construction | 2002 |
| Millennium Court (Woking) Management Limited | Households | 1998 |
| Millennium Diet & Nutriceuticals Limited | Professional & scientific | 1999 |
| Millennium Dough Solutions Limited | Manufacturing | 2026 |
| Miller's Property Holdings Limited | Real estate | 2019 |
| Millers Medical Services Ltd | Health & social care | 2021 |
| Millers Music Centre Limited | Wholesale & retail | 1966 |
| Millers Music Limited | Wholesale & retail | 1980 |
| Millers of Cambridge Limited | Transport & logistics | 1992 |
| MILLGATE2026 Ltd | Wholesale & retail | 2026 |
| Millianaro Ltd | Wholesale & retail | 2025 |
| Millington Churchill Ltd | Construction | 2024 |
| Millington Place Management Limited | Households | 2021 |
| Million Way Technology Limited | Extraterritorial | 2013 |
| Millo Appliances Limited | Wholesale & retail | 2017 |
| Millpark Services Limited | Real estate | 1990 |
| Millroad Limited | Professional & scientific | 2023 |
| Millroad Takeaway Ltd | Hospitality | 2020 |
| Mills & Saunders Plastering Limited | Construction | 2009 |
| Mills Healthcare Limited | Health & social care | 2014 |
| Millside Grange (Croxley Green) Management Company Limited | Households | 2023 |
| Millworks Ltd | Wholesale & retail | 2016 |
| Milton Court (Cambridge) Limited | Real estate | 2003 |
| Milton Hall Cambridge Limited | Other services | 2013 |
| Milton Hall Estates Limited | Real estate | 1998 |
| Milton Hall Holdings Limited | Financial services | 2013 |
| Milton Precision Engineering Limited | Professional & scientific | 2004 |
| Milton Spice Ltd | Hospitality | 2024 |
| MIM PFS Ltd | Health & social care | 2024 |
| Mimi's World Limited | Information & communication | 2019 |
| Mimicrete Ltd | Professional & scientific | 2021 |
| Mimona Selenites & Fossils Ltd | Wholesale & retail | 2016 |
| Mims Properties Limited | Real estate | 2023 |
| MIN Limited | Real estate | 1995 |
| Mina AI Ltd | Information & communication | 2026 |
| Mind Matter Development Ltd | Wholesale & retail | 2020 |
| Mindfulai Limited | Information & communication | 2020 |
| Mindicraft Limited | Professional & scientific | 2021 |
| Mindplai Ltd | Information & communication | 2026 |
| Mindraft Limited | Professional & scientific | 2008 |
| Mindsetter Ltd | Professional & scientific | 2010 |
| Mindtrackers Limited | Other services | 2014 |
| Mineroluk Ltd | Wholesale & retail | 2022 |
| Minerva Analysis Ltd | Other services | 2018 |
| Minerva Management Company Limited | Real estate | 2005 |
| Minerva Testing Limited | Information & communication | 2019 |
| Ming Homes UK Ltd | Construction | 2015 |
| Ming JUN (Tianjin) Company Limited | Wholesale & retail | 2025 |
| Ming Yang Shipping Co., Ltd | Extraterritorial | 2017 |
| Mingchengde E-Commerce Co., Ltd | Wholesale & retail | 2025 |
| Mingle Lane Residents Association Limited | Households | 1973 |
| Mingo Food Truck Ltd | Hospitality | 2022 |
| Mini ALL Stars Limited | Education | 2025 |
| Mini Bar Services Ltd | Manufacturing | 2022 |
| Mini Signing Ltd | Professional & scientific | 2018 |
| Mini-Tex Garment Co., Ltd | Wholesale & retail | 2023 |
| Minj and Ekka Limited | Hospitality | 2023 |
| Minogame Limited | Information & communication | 2021 |
| Mint Diagnostics Ltd | Health & social care | 2016 |
| Mintz Desserts Ltd | Wholesale & retail | 2022 |
| Miplanta Ltd | Professional & scientific | 2026 |
| Mira! Veterinary Diagnostic Imaging Ltd | Professional & scientific | 2014 |
| Mirabilis Management Limited | Professional & scientific | 2012 |
| Miracle Baby (UK) Limited | Wholesale & retail | 2023 |
| Mirai Development Limited | Information & communication | 2017 |