| Maray Energy Solutions Ltd | Administrative & support | 2024 |
| Marblehead Home Limited | Extraterritorial | 2021 |
| Marbow Properties Ltd | Real estate | 2018 |
| Marbs 2024 Ltd | Administrative & support | 2023 |
| Marca Fashions Ltd | Wholesale & retail | 2025 |
| Marcel Consultant's Limited | Wholesale & retail | 2022 |
| Marcella’S Aesthetics Ltd | Other services | 2025 |
| March for the Arts Ltd | Arts & recreation | 2020 |
| March IT Solutions Limited | Information & communication | 2010 |
| Marcia Makeup Ltd | Other services | 2025 |
| Marciac Health & Safety Services Ltd | Professional & scientific | 2013 |
| Marciac Lift Services Ltd | Administrative & support | 2003 |
| Marcin Pudlo Transport Ltd. | Transport & logistics | 2014 |
| Marcin Wolski Transport Ltd. | Transport & logistics | 2016 |
| Marcloud Limited | Information & communication | 2018 |
| Marco NW Ltd | Hospitality | 2020 |
| Marcom West Ltd | Information & communication | 2025 |
| Marcpol Transport Ltd | Transport & logistics | 2016 |
| Marcus Nicholas Consultancy Ltd | Professional & scientific | 2025 |
| Mardina Signature Group Limited | Real estate | 2026 |
| Mardis Properties Limited | Real estate | 2024 |
| Mareham Lane Solar Limited | Energy | 2022 |
| Mareno Capital Ltd | Other services | 2020 |
| Marfo Fish Limited | Hospitality | 2023 |
| Marford Properties Limited | Real estate | 1958 |
| Marg & Magz Limited | Hospitality | 2026 |
| Margaret Collis Trading Limited | Professional & scientific | 2017 |
| Margaux Siena Limited | Hospitality | 2024 |
| Margs Cafe Ltd | Hospitality | 2025 |
| Marguerite Laboratories Limited | Health & social care | 2021 |
| Marhaba Mini Market Liverpool Ltd | Wholesale & retail | 2024 |
| Mari Gold Beauty Salon Ltd | Other services | 2025 |
| Maria Atkinson Ltd | Health & social care | 2020 |
| Maria Fogg Family Law Ltd | Professional & scientific | 2011 |
| Maria KOS Ltd | Hospitality | 2025 |
| Maria Nelligan Consultancy Limited | Professional & scientific | 2025 |
| Maria Teresa DA Coreggio Ltd | Administrative & support | 2024 |
| Maria& Cleaning Ltd | Administrative & support | 2025 |
| Mariana Benavides Limited | Arts & recreation | 2020 |
| Maricelo Good Limited | Transport & logistics | 2026 |
| Marie's Aesthetics Limited | Health & social care | 2017 |
| Marillion Exchange Limited | Hospitality | 2022 |
| Marina Scuba School Limited | Education | 2023 |
| Marinade Ltd | Hospitality | 2026 |
| Marine Association Football Club Limited | Arts & recreation | 2025 |
| Marine Crescent 1969 Limited | Extraterritorial | 2014 |
| Marine Engineering Technical Services Limited | Professional & scientific | 2015 |
| Marine Holiday Park Limited | Hospitality | 2007 |
| Marine House (Mariners Wharf) Limited | Real estate | 2004 |
| Marine Lifting and Rigging Limited | Transport & logistics | 2014 |
| Marine Park Management Limited | Real estate | 2010 |
| Marine Salvage Ltd | Real estate | 2021 |
| Mariner Property Co Limited | Real estate | 2023 |
| Mariners Way (South Ferry Island) Management Company Limited | Households | 1999 |
| Mario Clad Ltd | Manufacturing | 2018 |
| Mario Healthcare Limited | Health & social care | 2018 |
| Mario's Grill Ltd | Hospitality | 2025 |
| Marioclad-Pfp Ltd | Construction | 2025 |
| Marion Mason Ingram Walker Sine Tributum Trading Limited | Professional & scientific | 2017 |
| Marios 218 Top Fades Ltd | Other services | 2024 |
| MARIOTRANS3103 Limited | Transport & logistics | 2025 |
| Maris Stella Sailing Limited | Wholesale & retail | 2020 |
| Maritime Pioneers Ltd | Professional & scientific | 2023 |
| Maritimevision Ltd | Administrative & support | 2019 |
| Marius Caliciu HGV Trans Ltd | Transport & logistics | 2018 |
| Marius Logi-Trans Ltd | Transport & logistics | 2019 |
| Marius Oprea UK Ltd | Transport & logistics | 2023 |
| Mariusz Blicharz Ltd | Transport & logistics | 2014 |
| Mariusz Radomski Transport Ltd. | Transport & logistics | 2014 |
| Mark Aitchison & SON Ltd | Construction | 2017 |
| Mark Alexander Property Services Ltd | Construction | 2019 |
| Mark Anthony 2 Developments Ltd | Construction | 2022 |
| Mark Anthony 3 Developments Ltd | Construction | 2022 |
| Mark Anthony Developments Limited | Construction | 2021 |
| Mark Bligh Ltd | Energy | 2015 |
| Mark Brooks Plastering Limited | Construction | 2018 |
| Mark Butchard Business Solutions Ltd | Administrative & support | 2012 |
| Mark Clinton Project Services Ltd | Construction | 2024 |
| Mark Court Joinery Limited | Construction | 2026 |
| Mark Dawson Hairdressing Ltd | Other services | 2017 |
| Mark Dinnen Hospitality Ltd | Real estate | 2025 |
| Mark Dowling Property & Finance Ltd | Financial services | 2014 |
| Mark Ennis Ltd | Transport & logistics | 2025 |
| Mark Gillette Interior Design Ltd | Arts & recreation | 1988 |
| Mark Gower Limited | Construction | 2010 |
| Mark Harrington Ltd | Professional & scientific | 2020 |
| Mark Hourston Consultancy Ltd | Health & social care | 2018 |
| Mark Ingham Limited | Professional & scientific | 2016 |
| Mark Johnson Consultancy Ltd | Health & social care | 2024 |
| Mark Johnston Engineering Limited | Construction | 2013 |
| Mark Jones and Partners Limited | Administrative & support | 2016 |
| Mark Kenny Lighting Consultancy Limited | Professional & scientific | 2023 |
| Mark Lennon Ltd | Other services | 2024 |
| Mark Mclorinan Consultancy Services Ltd | Professional & scientific | 2025 |
| Mark Peter Hodge Ltd | Extraterritorial | 2024 |
| Mark Property Group Limited | Construction | 2016 |
| Mark Reed Nationwide Services Limited | Administrative & support | 2020 |
| Mark Reynolds Holdings Limited | Professional & scientific | 2024 |
| Mark Reynolds Solicitors Limited | Professional & scientific | 2011 |
| Mark Scanlon Limited | Financial services | 2015 |