| Marie Star Consultancy Limited | Construction | 2018 |
| Marielle Ltd | Information & communication | 2025 |
| Marieshe Limited | Health & social care | 2015 |
| Marigolds Professional Cleaning Ltd | Administrative & support | 2018 |
| Marimonte Ltd | Hospitality | 2019 |
| Marin Recovery Ltd | Wholesale & retail | 2025 |
| Marina Home Services Ltd | Administrative & support | 2026 |
| Marina Motors (Leeds) Limited | Wholesale & retail | 2002 |
| Marina View Coffee Shop Ltd | Hospitality | 2025 |
| Marina's Room Ltd | Health & social care | 2025 |
| Marine Basin Management Company Limited | Households | 1995 |
| Marine World Aquatics Ltd | Wholesale & retail | 2020 |
| Marinexhub Ltd | Professional & scientific | 2024 |
| Marino Maritime Group Ltd | Transport & logistics | 2023 |
| Mario&Trans Ltd | Transport & logistics | 2020 |
| Marioway Benefits Consultancy Ltd | Professional & scientific | 2020 |
| Marioxvx Ltd | Transport & logistics | 2025 |
| Maris Street Motors Limited | Wholesale & retail | 2009 |
| Marits Media Limited | Professional & scientific | 2018 |
| Marius Alina Ltd | Professional & scientific | 2026 |
| Marius Barbu Ltd | Transport & logistics | 2025 |
| Marius Cristian Pitea Ltd | Transport & logistics | 2021 |
| Marius Enterprise Ltd | Construction | 2025 |
| Marius Top Drive Ltd | Transport & logistics | 2026 |
| Marius UK Delivery Ltd | Transport & logistics | 2024 |
| Mariusx Courier Ltd | Transport & logistics | 2026 |
| Mark Aspin Electrical Compliance Ltd | Professional & scientific | 2026 |
| Mark B Haulage Ltd | Transport & logistics | 2011 |
| Mark Beck Advice Limited | Financial services | 2024 |
| Mark Brealey Communications Ltd | Manufacturing | 2018 |
| Mark Brennan Civil Engineering Limited | Construction | 2013 |
| Mark Broadbent Electrical Limited | Construction | 2026 |
| Mark Car Park Ltd. | Administrative & support | 2017 |
| Mark Catley Limited | Information & communication | 2011 |
| Mark Emmett Properties Limited | Real estate | 1999 |
| Mark Fielding Consulting Limited | Professional & scientific | 2013 |
| Mark Fisher Health & Safety Consulting Ltd | Professional & scientific | 2024 |
| Mark Frudd Illustration Limited | Professional & scientific | 2015 |
| Mark Fuller Limited | Administrative & support | 2002 |
| Mark Gregory Smith Ltd | Extraterritorial | 2024 |
| Mark Hawke Limited | Construction | 2010 |
| Mark Hobson Commercial Services Limited | Professional & scientific | 2019 |
| Mark Jayne Property Ltd | Real estate | 2024 |
| Mark Johnson Consulting Ltd | Real estate | 2013 |
| Mark Laine-Toner Consulting Ltd | Professional & scientific | 2023 |
| Mark Leeds Ltd | Real estate | 2024 |
| Mark Lewis Investments Ltd | Real estate | 2025 |
| Mark Malley Transport Limited | Transport & logistics | 2007 |
| Mark Neave Demolition Limited | Wholesale & retail | 2006 |
| Mark of Success UK Limited | Real estate | 2017 |
| Mark Proudfoot Investments Ltd | Financial services | 2016 |
| Mark Robinson Wealth Management Ltd | Financial services | 2022 |
| Mark Royston Contracting Limited | Professional & scientific | 2005 |
| Mark S Building Contractor Limited | Construction | 2004 |
| Mark Simon Designs Ltd | Wholesale & retail | 2016 |
| Mark Smith Ltd | Extraterritorial | 2025 |
| Mark Stacey Limited | Extraterritorial | 1964 |
| Mark Stewart Ltd | Transport & logistics | 2009 |
| Mark Thompson (Leeds) Limited | Construction | 2001 |
| Mark Townsend Golf Ltd | Information & communication | 2020 |
| Mark Vernon Wealth Management Limited | Financial services | 2003 |
| Mark Vidal Properties Ltd | Real estate | 2023 |
| Mark Warner Properties Limited | Real estate | 2015 |
| Mark Wilcox Consulting Limited | Health & social care | 2010 |
| Markelio Ltd | Professional & scientific | 2026 |
| Market Deck Ltd | Professional & scientific | 2024 |
| Market Media (Yorkshire) Ltd | Professional & scientific | 2025 |
| Market Refrigeration Services Limited | Manufacturing | 1985 |
| Market Square Tavern Ltd | Hospitality | 2020 |
| Market Town Taverns Limited | Hospitality | 1998 |
| Marketbest Limited | Construction | 1989 |
| Marketing Bradford Ltd | Professional & scientific | 2016 |
| Marketing by Aurora Ltd | Professional & scientific | 2023 |
| Marketing Force 1 Ltd | Financial services | 2020 |
| Marketing Handled Ltd | Professional & scientific | 2026 |
| Marketing Ventures Limited | Professional & scientific | 2021 |
| Marketingly Ltd | Administrative & support | 2025 |
| Marketplace Brand Realisation Limited | Information & communication | 2017 |
| Marketplace Mortgages Ltd | Financial services | 2017 |
| Marketshare Partners Emea, Ltd | Administrative & support | 2009 |
| Marketworks Ltd | Professional & scientific | 2025 |
| Markeyto Ltd | Manufacturing | 2023 |
| Markham & Rylett Limited | Hospitality | 2016 |
| Markhor Interiors Ltd | Construction | 2023 |
| Marksman Cctv Services Limited | Administrative & support | 2023 |
| Marktly Ltd | Wholesale & retail | 2025 |
| Marlene Scott Ltd | Real estate | 2024 |
| Marley & ME Dog Walking Company Ltd | Agriculture & fishing | 2021 |
| Marley Design and Build Ltd | Construction | 2025 |
| Marlie Holdings Limited | Financial services | 2022 |
| Marlin Barber Ltd | Other services | 2026 |
| Marlite UK Ltd | Wholesale & retail | 2017 |
| Marloco Holdings Ltd | Financial services | 2020 |
| Marloco Limited | Health & social care | 1994 |
| Marlou Property Ltd | Real estate | 2025 |
| Marlston Limited | Information & communication | 2025 |
| Marmaris Bistro Ltd | Hospitality | 2023 |
| Marmig & BOB Ltd | Health & social care | 2022 |
| Marnmedia Ltd | Professional & scientific | 2020 |
| Maroshola Healthcare Limited | Health & social care | 2022 |