| MK Flames Ltd | Hospitality | 2025 |
| MK Lifestyle Ltd | Health & social care | 2021 |
| MK Nexa Ltd | Wholesale & retail | 2026 |
| MK Primecare Ltd | Wholesale & retail | 2025 |
| MK Trucks Ltd | Wholesale & retail | 2023 |
| MK Yorkshire Ltd | Hospitality | 2022 |
| Mkastos Holdings Ltd | Transport & logistics | 2022 |
| Mkay Music Limited | Arts & recreation | 2013 |
| MKD Properties (Sheffield) Holdings Limited | Financial services | 2007 |
| MKD Properties (Sheffield) Limited | Real estate | 2007 |
| Mkdm Estates Limited | Real estate | 2023 |
| MKG Lettings Ltd | Hospitality | 2026 |
| MKG107 Ltd | Real estate | 2026 |
| MKH Groups Limited | Information & communication | 2025 |
| Mkhempire Limited | Wholesale & retail | 2025 |
| MKM Consultancy & Property Ltd | Construction | 2023 |
| Mkpedem Business Consulting Ltd | Professional & scientific | 2026 |
| MKS Taxis Ltd | Transport & logistics | 2026 |
| MKT Travels Ltd | Transport & logistics | 2025 |
| ML Mortgage Advice Ltd | Financial services | 2026 |
| ML Transport (NL) Ltd | Wholesale & retail | 2019 |
| MLA Performance Ltd | Education | 2023 |
| MLA Roses UK Ltd | Wholesale & retail | 2025 |
| Mlas Services Ltd | Administrative & support | 2024 |
| Mlaw Holdings Ltd | Professional & scientific | 2021 |
| MLB Ceilings Limited | Construction | 2015 |
| MLC Innovations Limited | Information & communication | 2024 |
| MLC Mortgage Services Ltd | Financial services | 2026 |
| Mlfpm Ltd | Professional & scientific | 2018 |
| MLG Digital Ltd | Information & communication | 2022 |
| MLH Legal Limited | Professional & scientific | 2026 |
| Mliso Ltd | Administrative & support | 2021 |
| MLK Leisure Limited | | 2010 |
| Mlmaia Property Developments Ltd | Real estate | 2022 |
| Mlnr Prime Estates Limited | Real estate | 2026 |
| MLP Arts Ltd | Arts & recreation | 2011 |
| MLS Contracts Ltd | Arts & recreation | 2010 |
| MLS Wholesale Ltd | Wholesale & retail | 2026 |
| Mlungisi Nyathi Ltd | Administrative & support | 2015 |
| Mlux Consulting Limited | Professional & scientific | 2023 |
| Mlvltd Events Limited | Arts & recreation | 2024 |
| MM Electronics Ltd | Wholesale & retail | 2020 |
| MM GAS Turbine Services Limited | Manufacturing | 2013 |
| MM Lopes Ltd | Administrative & support | 2025 |
| MM News & Booze Limited | Wholesale & retail | 2024 |
| MM Takeaways Limited | Hospitality | 2023 |
| MMA Electrical Ltd | Construction | 2025 |
| Mmakanjera Limited | Public administration | 2014 |
| MMD Plastering & Paint Ltd | Construction | 2023 |
| MMF Property Developments Ltd | Real estate | 2024 |
| MMG Tyres & Wheels Limited | Wholesale & retail | 2018 |
| Mmjj Limited | Other services | 2023 |
| MMK Telecommunications Ltd | Information & communication | 2013 |
| MMM Aviation Services Ltd | Transport & logistics | 2026 |
| Mmmp Holdings Limited | Financial services | 2022 |
| Mmmr Leisure Limited | Administrative & support | 2024 |
| Mmor Limited | Real estate | 2025 |
| MMS (Sheffield) Limited | Construction | 2008 |
| MMS Electrical Solutions Ltd | Construction | 2009 |
| MMT Property Co. Limited | Real estate | 2026 |
| Mmtreescape Tree Services Ltd | Other services | 2015 |
| MMU Ltd | Health & social care | 2015 |
| Mmxv Couriers Limited | Transport & logistics | 2015 |
| Mmxx Dynamics Ltd. | Information & communication | 2018 |
| MNA Executive Close Protection Services Ltd | Administrative & support | 2022 |
| Mnazir OBE Ltd | Hospitality | 2022 |
| MNC Delivery Ltd | Transport & logistics | 2019 |
| Mnci Ltd | Health & social care | 2024 |
| Mnen Ltd | Administrative & support | 2017 |
| MNH Maintenance Services Ltd | Real estate | 2024 |
| MNK Property Investments Ltd | Construction | 2022 |
| Mnkv Limited | Real estate | 2024 |
| MNM Global Ltd | Wholesale & retail | 2023 |
| MNS Developments Midlands Limited | Real estate | 2023 |
| MNS Freight Services Limited | Transport & logistics | 2008 |
| MNS Plumbing Ltd | Wholesale & retail | 2022 |
| MNU Deliveries Ltd | Transport & logistics | 2026 |
| Mnzl Logistics Limited | Manufacturing | 2026 |
| MO & YAS Estates Limited | Real estate | 2025 |
| MO 47 Ltd | Hospitality | 2026 |
| MO Plumbing and Heating Ltd | Construction | 2019 |
| Mo's Barbers 1 Ltd | Other services | 2026 |
| Moabode Property Group Ltd | Wholesale & retail | 2026 |
| Moat Builders Artificial Intelligence Ltd | Information & communication | 2018 |
| Mobiceller Limited | Wholesale & retail | 2023 |
| Mobile Mechanical Services (Dinnington) Ltd | Wholesale & retail | 2008 |
| Mobile Minds by Design Limited | Education | 2014 |
| Mobile Phones and Repairs Spital Hill Ltd | Wholesale & retail | 2021 |
| Mobile Power Ltd | Manufacturing | 2013 |
| Mobile Repair Doctor Ltd | Manufacturing | 2025 |
| Mobius Commercial Finance Limited | Financial services | 2025 |
| Moca Restaurants Ltd | Hospitality | 2019 |
| Mocca Education Ltd | Public administration | 2023 |
| Mochachos Ltd | Hospitality | 2026 |
| Mocino Limited | Professional & scientific | 1982 |
| Modacity Limited | Administrative & support | 2008 |
| Mode.Lyf CIC | Administrative & support | 2025 |
| Modedrive Limited | Wholesale & retail | 1983 |
| Modena Recordings Limited | Information & communication | 2002 |
| Modena Records Limited | Information & communication | 1997 |