| Mark Hamilton Communications Limited | Professional & scientific | 2014 |
| Mark Hanson Formwork Ltd | Construction | 2014 |
| Mark Hendy Car Repairs Limited | Wholesale & retail | 2004 |
| Mark Invest UK Ltd | Information & communication | 2016 |
| Mark John Hughes Ltd | Construction | 2026 |
| Mark Jones Bricklaying Ltd | Construction | 2019 |
| Mark Kelly Property Maintenance Ltd | Construction | 2019 |
| Mark Kidel Films Limited | Information & communication | 2001 |
| Mark Leaver Consulting Limited | Professional & scientific | 2010 |
| Mark Manning Access Ltd | Professional & scientific | 2013 |
| Mark Marlow Limited | Arts & recreation | 2017 |
| Mark Mclean & Co Limited | Professional & scientific | 2002 |
| Mark Neath Consulting Ltd | Professional & scientific | 2022 |
| Mark Neathway Ltd | Professional & scientific | 2013 |
| Mark Newman Drylining Limited | Construction | 2023 |
| Mark Powell Fabrications Ltd | Manufacturing | 2014 |
| Mark Pygott MW Consulting Ltd | Professional & scientific | 2020 |
| Mark Richard (Brokers) Limited | Financial services | 1964 |
| Mark Roper Consulting Limited | Financial services | 2011 |
| Mark Sanders Golf Limited | Wholesale & retail | 2016 |
| Mark Stone Technical Services Limited | Professional & scientific | 2013 |
| Mark Swanwick Associates Limited | Professional & scientific | 1998 |
| Mark Vincent Surveying Limited | Professional & scientific | 2013 |
| Mark'D With INK Limited | Other services | 2016 |
| Mark's Mobility Services & Repairs Limited | Administrative & support | 2003 |
| MARK43 UK Limited | Information & communication | 2021 |
| Marka Restuarent and Cafe Limited | Hospitality | 2014 |
| Marker Properties Limited | Real estate | 2023 |
| Market Drayton Battery Storage Limited | Energy | 2023 |
| Market Drive Ltd | Information & communication | 2026 |
| Market Lane Private Limited | Real estate | 2025 |
| Market Place N2 RTM Company Limited | Administrative & support | 2015 |
| Market Square Catering Easter Compton Ltd | Hospitality | 2016 |
| Market Trend 4U Limited | Wholesale & retail | 2025 |
| Market Veterinary Centre Limited | Extraterritorial | 2005 |
| MARKET4ALL Ltd | Wholesale & retail | 2024 |
| Marketing Adviser Ltd | Extraterritorial | 2014 |
| Marketing and Creative Handbook Online Ltd | Information & communication | 2020 |
| Marketing Branch Ltd | Administrative & support | 2017 |
| Marketing Consultancy & Services "Marcoser" | | 2006 |
| Marketing Dynamo Ltd | Professional & scientific | 2026 |
| Marketing Global Influence Ltd | Professional & scientific | 2025 |
| Marketing Procurement Consulting Limited | Administrative & support | 2016 |
| Marketio Ltd | Wholesale & retail | 2026 |
| Marketplace Systems Limited | Education | 2026 |
| Marketpool Limited | Wholesale & retail | 2001 |
| Markets JC Limited | Households | 2009 |
| Marketwatch Ltd | Financial services | 2023 |
| Markey Health Care Services Limited | Health & social care | 2024 |
| Markham Estates Limited | Real estate | 2013 |
| Markhands Ltd | Extraterritorial | 2009 |
| Markkidley.Com Limited | Information & communication | 2014 |
| Marklands Management Company Limited | Households | 1984 |
| Markmoor Limited | Agriculture & fishing | 1979 |
| Marko Nurminen Limited | Professional & scientific | 2011 |
| Marko Property Investment Ltd | Real estate | 2024 |
| Markpharm Ltd | Health & social care | 2020 |
| Marks OUT of Tenancy Limited | Information & communication | 2015 |
| Marksbury Consulting Limited | Construction | 2009 |
| Marksbury Medical Group Limited | Real estate | 2017 |
| Marksman Security Ltd. | Construction | 2005 |
| Markson & Sons Limited | Real estate | 2018 |
| Markson Construction Limited | Construction | 2024 |
| Markson Floors Ltd | Construction | 2017 |
| Markson Joinery Limited | Manufacturing | 2026 |
| Markson Property Management Limited | Real estate | 2025 |
| Marku Home Developments Limited | Real estate | 2025 |
| Marky Marks Mobile Butchers Ltd | Wholesale & retail | 2025 |
| Marlabs Innovations Limited | Information & communication | 2022 |
| Marlborough Building Supplies Limited | Wholesale & retail | 2003 |
| Marlborough Facilities Limited | Construction | 2003 |
| Marlborough House BS2 9JX Management Company Ltd | Administrative & support | 2014 |
| Marlborough House Management Company (Bristol) Limited | Households | 1990 |
| Marlborough Mansions (Management Company) Limited | Households | 1985 |
| Marleberg Grange Management Company (Wiltshire) Limited | Real estate | 2017 |
| Marley Roofing Ltd | Construction | 2021 |
| Marley Roofing South West Ltd | Construction | 2026 |
| Marling Fish Bar Ltd | Hospitality | 2019 |
| Marling Road Management Company Limited | Households | 1980 |
| Marlinwatch Limited | Wholesale & retail | 2018 |
| Marloa Limited | Real estate | 2017 |
| Marloes Group Ltd | Real estate | 2020 |
| Marlon Jackson Financial Services Ltd | Financial services | 2025 |
| Marmaduke Nominees Limited | Professional & scientific | 2012 |
| Marmalade Arts Ltd | Wholesale & retail | 2023 |
| Marmita DA Mamys Ltd | Hospitality | 2020 |
| Marmobello Ltd | Construction | 2009 |
| Maroman Ltd | Real estate | 2025 |
| Maronia Properties Ltd | Real estate | 2023 |
| Maroon Films Bristol Ltd | Information & communication | 2024 |
| Marpa Ltd | Transport & logistics | 2025 |
| Marpe Solutions Limited | Professional & scientific | 2023 |
| Marpis Ltd | Transport & logistics | 2014 |
| Marples Construction Limited | Construction | 1907 |
| Marples Developments Limited | Construction | 2001 |
| Marquee Master Limited | Wholesale & retail | 2011 |
| Marr Engineering Limited | Manufacturing | 1998 |
| Marr Masonry Ltd | Construction | 2025 |
| Marr Rentals Ltd | Real estate | 2018 |
| Marrune Living Limited | Real estate | 2022 |