| Milmar Decorators Ltd | Construction | 2024 |
| Milon Group Ltd | Financial services | 2023 |
| Milosz Kaczmar Ltd | Transport & logistics | 2018 |
| Milstow Electrical Ltd | Construction | 2017 |
| Milton & Shaw Associates Limited | Information & communication | 2003 |
| Milton Creed Limited | Information & communication | 2025 |
| Milton Grove Management Limited | Households | 2015 |
| MIM Cells UK Limited | Other services | 2017 |
| Mimicry Ltd | Wholesale & retail | 2023 |
| Mimo Consulting Limited | Construction | 2015 |
| Mind Restoration Practice CIC | Health & social care | 2022 |
| Mindcare Medical Limited | Health & social care | 2024 |
| Mindful Fitmum Hub Ltd | Education | 2026 |
| Mindler Ltd | Health & social care | 2019 |
| Mindler Sandbox Limited | Health & social care | 2021 |
| Mindsight Coaching (UK) LLP | | 2013 |
| Mindsparks Learning Ltd | Education | 2025 |
| Mindspirit Ltd | Wholesale & retail | 2024 |
| Mindwise Consulting Ltd | Other services | 2024 |
| Minella Limited | Professional & scientific | 2021 |
| Mineral Check Limited | Health & social care | 2001 |
| Minerva Creative Marketing Limited | Professional & scientific | 2014 |
| Mingle Mechanical & Plumbing Limited | Construction | 2024 |
| Mini Soil Surveys (London) Ltd | Construction | 2006 |
| Mini Stop Ltd | Wholesale & retail | 2025 |
| Minipros Limited | Arts & recreation | 2025 |
| Minority Broker Partnerships 10 Limited | Financial services | 2026 |
| Minority Broker Partnerships 2 Limited | Financial services | 2025 |
| Minority Broker Partnerships 3 Limited | Financial services | 2025 |
| Minority Broker Partnerships 4 Limited | Financial services | 2025 |
| Minority Broker Partnerships 5 Limited | Financial services | 2025 |
| Minority Broker Partnerships 6 Limited | Financial services | 2025 |
| Minority Broker Partnerships 7 Limited | Financial services | 2025 |
| Minority Broker Partnerships 8 Limited | Financial services | 2025 |
| Minority Broker Partnerships 9 Limited | Financial services | 2026 |
| Minority Broker Partnerships Limited | Financial services | 2025 |
| Minority Venture Partners 11 Limited | Financial services | 2019 |
| Minority Venture Partners 12 Limited | Financial services | 2021 |
| Minority Venture Partners 13 Limited | Financial services | 2022 |
| Minority Venture Partners 14 Limited | Financial services | 2022 |
| Minority Venture Partners 16 Limited | Financial services | 2023 |
| Minority Venture Partners 17 Limited | Financial services | 2023 |
| Minority Venture Partners 18 Limited | Financial services | 2023 |
| Minority Venture Partners 19 Limited | Financial services | 2025 |
| Minority Venture Partners 6 Limited | Financial services | 2017 |
| Minority Venture Partners 9 Limited | Financial services | 2015 |
| Mint EST Ltd | Hospitality | 2018 |
| Miramar HC Limited | Professional & scientific | 2011 |
| Miscellaneum Ltd | Wholesale & retail | 2017 |
| Miss Mercator Ltd | Wholesale & retail | 2022 |
| Mission & Relief Logistics Ltd | Transport & logistics | 2008 |
| Mission Cycles Limited | Wholesale & retail | 2008 |
| Mission PAY Co Ltd | Administrative & support | 2024 |
| Mistral Professional Services Ltd | Information & communication | 2022 |
| Mitandi Limited | Professional & scientific | 2010 |
| Mitchell & Carne Systematic Training Consultants Ltd | Health & social care | 2011 |
| Mitchell and Peach Limited | Manufacturing | 2010 |
| Mittshis Ltd | Hospitality | 2021 |
| Mivar Energy Ltd | Professional & scientific | 2026 |
| Mixrepairs Ltd | Manufacturing | 2010 |
| Miyazawa (UK) Limited | Other services | 2007 |
| Mizon Properties Limited | Real estate | 2016 |
| Mizons Travel Limited | Administrative & support | 2021 |
| MJ Driving School Ltd | Education | 2024 |
| MJ Management and Business Consultancy Ltd | Professional & scientific | 2021 |
| MJ Timeless Limited | | 2010 |
| MJ Trading AB (UK) Ltd | Wholesale & retail | 2025 |
| Mj/Kb Ltd | Transport & logistics | 2020 |
| MJA Sports Consultancy Ltd | Information & communication | 2021 |
| MJC Contractors Kent Limited | Construction | 2018 |
| MJH Industrial Roofing Ltd | Construction | 2022 |
| MJL (Kent) Limited | Construction | 2020 |
| MJM Consultants Limited | Information & communication | 2022 |
| MJP Unique Developments Ltd | Construction | 2023 |
| MJT Scaffolding Ltd | Construction | 2020 |
| Mjvd Holdco Limited | Financial services | 2019 |
| MK Drive UK Limited | Transport & logistics | 2015 |
| MK Logistics 247 Ltd | Transport & logistics | 2023 |
| MK Recovering Solutions Ltd | Water & waste | 2021 |
| MKD Education Ltd | Education | 2026 |
| Mkenzie Ltd | Construction | 2024 |
| Mkhyper Ltd | Wholesale & retail | 2021 |
| MKM Buildings Supplies (Holdings) Ltd | Wholesale & retail | 2026 |
| MKM Delivery Ltd | Transport & logistics | 2024 |
| Mldc Property Holdings Ltd | Real estate | 2024 |
| MLN Estrent Ltd | Professional & scientific | 2026 |
| MLT Environmental Services Ltd | Water & waste | 2018 |
| MM Catering and Events Limited | Hospitality | 2019 |
| MM Social Care Consultancy Ltd | Health & social care | 2023 |
| Mmcd Ltd | Hospitality | 2024 |
| MMH Ventures Ltd | Wholesale & retail | 2020 |
| MMM94 Ltd | Water & waste | 2017 |
| MMMM2024 Ltd | Transport & logistics | 2024 |
| MMS (Kent) Ltd | Transport & logistics | 2015 |
| MN Building Services Ltd | Construction | 2021 |
| MNA and GM Partnership LLP | | 2025 |
| MNA Development Properties Ltd | Construction | 2021 |
| MNA Distribution Ltd | Transport & logistics | 2021 |
| MNA Logistics Ltd | Transport & logistics | 2015 |
| Mnlm Properties Limited | Real estate | 2012 |