| Mainprize Offshore Ltd | Transport & logistics | 1979 |
| Mainprize Offshore Three Limited | Other services | 2026 |
| Mainprize Offshore Two Ltd | Transport & logistics | 2024 |
| Maison Lume Ltd | Wholesale & retail | 2025 |
| Major Joinery & Caravan Sundecks Limited | Construction | 2017 |
| Major Joinery Limited | Construction | 2022 |
| Makersmith Limited | Extraterritorial | 2015 |
| Makin Construction Careers Ltd | Administrative & support | 2026 |
| Malik Vapes Ltd | Wholesale & retail | 2025 |
| Mallorys Ltd | Wholesale & retail | 2018 |
| Malton and Ryedale Farmers Livestock Market Limited | Professional & scientific | 2012 |
| Management Development Group Ltd | Professional & scientific | 2022 |
| Mandx Partners Ltd | Construction | 2011 |
| Manor Farm Cottages Scarborough Ltd | Hospitality | 2023 |
| Manor Farm Livery (Hutton Buscel) Ltd | Arts & recreation | 2011 |
| Manor Farm Park Storage Limited | Real estate | 2019 |
| Manor Farm Property Limited | Real estate | 2019 |
| Marcus Anthony Furnishings Limited | Wholesale & retail | 2015 |
| Marine Recoveries Limited | Professional & scientific | 2020 |
| Marine Sands Limited | Households | 2006 |
| Marine View Apartments Limited | Households | 2006 |
| Mariners House (Whitby) Management Company Limited | Households | 2016 |
| Maritime Apartments Management Limited | Households | 2025 |
| Maritime Apartments Scarborough Ltd | Hospitality | 2021 |
| Maritime Holiday Apartments Ltd | Hospitality | 2021 |
| Mark Branagan Limited | Information & communication | 2014 |
| Mark Ford Draughting Limited | Professional & scientific | 2015 |
| Mark Heslington Limited | Manufacturing | 2003 |
| Mark Jenkinson (Scarborough) Limited | Transport & logistics | 2024 |
| Mark Pryce Plumbing and Heating Limited | Construction | 2023 |
| Mark Stevenson (Scarborough) Limited | Real estate | 2015 |
| Mark Whiteley Holdings Limited | Financial services | 2009 |
| Marketing Associates Limited | Professional & scientific | 1998 |
| Marley Landrover Ltd | Wholesale & retail | 2019 |
| Marlosc Drives Limited | Construction | 2025 |
| Marmion Healthcare Limited | Health & social care | 2018 |
| Marton-Hope Ltd | Financial services | 2019 |
| Marton-Hope Properties Ltd | Real estate | 2022 |
| Maryham Ltd | Real estate | 2025 |
| Matchpoint Tennis Ltd | Arts & recreation | 2007 |
| Mates Creates Limited | Wholesale & retail | 2022 |
| Matiga Limited | Extraterritorial | 2010 |
| Matt Group Ltd | Financial services | 2022 |
| Matty Harrison Construction Limited | Construction | 2022 |
| Maurice Trading Ltd | Wholesale & retail | 2025 |
| MAX Power Electrical Limited | Construction | 2012 |
| Maximus Venues Ltd | Hospitality | 2023 |
| Maxtone Ltd | Arts & recreation | 2011 |
| Maya Tech Ltd | Information & communication | 2019 |
| Mayholme Apartments Management Company Limited | Households | 2018 |
| Mbasa Limited | Health & social care | 2015 |
| MBF RAW Ltd | Wholesale & retail | 2022 |
| MBS Accountancy Limited | Professional & scientific | 2001 |
| MBX Media Ltd | Information & communication | 2020 |
| MBX Pro Ltd | Information & communication | 2020 |
| MC Ventures Limited | Real estate | 2018 |
| Mcbean Property Management Limited | Households | 1990 |
| Mccain Farms of the Future G.B. Limited | Agriculture & fishing | 2025 |
| Mccain Foods (G.B.) Limited | Agriculture & fishing | 1962 |
| Mccain UK H1 Limited | Financial services | 2012 |
| Mccain UK H2 Limited | Financial services | 2012 |
| MCD Industrial Roofing Limited | Construction | 2021 |
| Mcmann Consultancy Limited | Professional & scientific | 2021 |
| MDG Property Ventures Ltd | Real estate | 2024 |
| Meadow Cottage Industries Limited | Administrative & support | 2003 |
| Mealtech Machinery Limited | Manufacturing | 2025 |
| Measure Time Limited | Manufacturing | 2005 |
| Meck Legal Limited | Professional & scientific | 2026 |
| Megamobil UK Ltd | Professional & scientific | 2024 |
| Megatheorem Limited | Administrative & support | 2014 |
| Melba Investments Ltd | Financial services | 2024 |
| Melba Properties Ltd | Real estate | 2024 |
| Melbeez Incorporated Ltd | Wholesale & retail | 2023 |
| Melrose Property Developments Limited | Real estate | 2003 |
| Melrose Street 1958 Limited | Extraterritorial | 2014 |
| Meltcloud Limited | Wholesale & retail | 2019 |
| Menon Corporation Ltd. | Education | 2013 |
| Mens Designer Clothes Online Limited | Extraterritorial | 2008 |
| MEP Building Ltd | Other services | 2025 |
| Merrydith Property Developments Ltd | Real estate | 2006 |
| Metal Box Vehicle Remarketing Limited | Wholesale & retail | 2020 |
| Metcalfe's Fresh Produce Ltd | Wholesale & retail | 2017 |
| Mfgb Limited | Financial services | 2026 |
| MFW 66 Holdings Limited | Financial services | 2023 |
| MFW 66 Limited | Wholesale & retail | 2010 |
| MH Works Ltd | Professional & scientific | 2024 |
| MH7 (Precision Engineering) Limited | Professional & scientific | 2011 |
| Mhdb Properties Ltd | Real estate | 2023 |
| Michael & Jessica Wedding Fashion Ltd | Manufacturing | 2021 |
| Michaela Engineering Ltd | Real estate | 2018 |
| Mick Paxton Architects Ltd | Professional & scientific | 2011 |
| Mickey the Brickey Limited | Construction | 2017 |
| Mike Kent Car & Van Sales (Scarborough) Limited | Wholesale & retail | 2002 |
| Millanos Ltd | Hospitality | 2026 |
| Millplus Limited | Wholesale & retail | 1999 |
| Mills Motorsport Ltd | Other services | 2023 |
| Millstone Consultancy Ltd | Information & communication | 2014 |
| Mind Goals Limited | Health & social care | 2022 |
| Mindpath Psychology Ltd | Health & social care | 2025 |
| Minim Digital Limited | Information & communication | 2021 |