| Medsam Limited | Health & social care | 2016 |
| Medskincoo Ltd | Other services | 2026 |
| Medtech Growth Ltd | Professional & scientific | 2022 |
| Medtraction Ltd | Professional & scientific | 2025 |
| Medusa Decor Limited | Construction | 2014 |
| Medwise AI Limited | Information & communication | 2019 |
| MEE Estates Ltd | Real estate | 2024 |
| Meeda Homes Ltd | Real estate | 2023 |
| Meedu Ltd | Education | 2019 |
| Meedu.Media Ltd | Education | 2023 |
| Meelars Limited | Information & communication | 2023 |
| Meema Makes Limited | Information & communication | 2023 |
| Meer Furniture Ltd | Wholesale & retail | 2024 |
| Meer Leeds Limited | Wholesale & retail | 2023 |
| Meereen IT Services Limited | Information & communication | 2016 |
| Meerkat Web Design Limited | Information & communication | 2013 |
| Meerkat Web Hosting Limited | Information & communication | 2013 |
| Meeson Roofing Ltd | Construction | 2024 |
| Mefm Limited | Professional & scientific | 2019 |
| MEG Marah Limited | Health & social care | 2016 |
| Mega Capital Holdings Ltd | Wholesale & retail | 2022 |
| Megagroup Logistic Services Limited | Financial services | 2025 |
| Megamart Solutions Ltd | Wholesale & retail | 2025 |
| Megan Collins Jewellery Ltd | Wholesale & retail | 2023 |
| Megan Rider Ltd | Other services | 2023 |
| Megapixel Photography Ltd | Professional & scientific | 2022 |
| Megatone Osteopathy Ltd | Health & social care | 2018 |
| Mehmood K Limited | Professional & scientific | 2025 |
| Meho Ltd | Professional & scientific | 2017 |
| Mehretab Limited | Administrative & support | 2022 |
| Mehrmed Limited | Health & social care | 2026 |
| Mehrunix Ltd | Professional & scientific | 2025 |
| Mehsahdi Limited | Wholesale & retail | 2022 |
| MEI Solutions Limited | Construction | 2019 |
| Meice Ltd | Professional & scientific | 2013 |
| Meif II CP Holdings 3 Limited | Professional & scientific | 2007 |
| Meif II CP SPV 1 Limited | Professional & scientific | 2012 |
| Meif II CP SPV 2 Limited | Professional & scientific | 2012 |
| Meighen & Co Limited | Wholesale & retail | 2024 |
| Meip Commercial Ltd | Real estate | 2019 |
| MEK Industries Ltd | Other services | 2015 |
| MEK Services Ltd | Administrative & support | 2016 |
| Meknar Ltd | Administrative & support | 2017 |
| Melaher Ltd | Real estate | 2025 |
| Melak Limited | Wholesale & retail | 2021 |
| Melanin Mix-Up Ltd | Hospitality | 2025 |
| Melay Music Limited | Arts & recreation | 2016 |
| Melbourne Ambrose Limited | Hospitality | 2022 |
| Meleady Properties Ltd | Real estate | 2025 |
| Melex Investments Ltd | Real estate | 2026 |
| Meliora Clinical Health Solutions Ltd | Health & social care | 2021 |
| Meliora Dental Limited | Health & social care | 2010 |
| Melissa Beauty & Beyond Ltd | Other services | 2025 |
| Melissa Café Ltd | Hospitality | 2026 |
| Mellex Limited | Hospitality | 2018 |
| Mellinium Investments | Financial services | 2020 |
| Mellor Brownlee Limited | Information & communication | 2025 |
| Melltarn Limited | Administrative & support | 2021 |
| Mellwood Kitchen Solutions Limited | Construction | 2021 |
| Melly Collins Limited | Professional & scientific | 2019 |
| Melo Advisory Services Limited | Professional & scientific | 2018 |
| Melo Tech UK Ltd | Wholesale & retail | 2024 |
| Melomaniac Records Limited | Information & communication | 2021 |
| Melomys Limited | Wholesale & retail | 2023 |
| Melon Books Group Ltd | Information & communication | 2026 |
| Melrose Digital Ltd | Information & communication | 2014 |
| Meltham Hall Management Limited | Administrative & support | 1998 |
| Melther Ltd | Information & communication | 2025 |
| Meltingpoint Ice Cream Ltd | Manufacturing | 2024 |
| Meltog (1952) Ltd | Manufacturing | 2010 |
| Meltog Ltd | Manufacturing | 2011 |
| Melville Automotive Limited | Extraterritorial | 2023 |
| Melville C.W. Limited | Water & waste | 1946 |
| Melville Design Limited | Extraterritorial | 2023 |
| Melvprop Limited | Real estate | 2025 |
| Melyn RS Ltd | Wholesale & retail | 2023 |
| Memax Ltd | Health & social care | 2021 |
| Meme Performance Ltd | Wholesale & retail | 2020 |
| Memento Ltd | Wholesale & retail | 2023 |
| Memo Proofing Ltd | Professional & scientific | 2025 |
| Memorints Limited | Professional & scientific | 2005 |
| Memory Care Limited | Administrative & support | 2011 |
| Memory Care Store Limited | Wholesale & retail | 2014 |
| Memory Lane Architectural Products Limited | Construction | 2013 |
| Memory Lane Day Care Limited | Health & social care | 2019 |
| Memory Lane Trust CIC | Health & social care | 2019 |
| Memoryworks Limited | Real estate | 2011 |
| Memuna Adam Consultancy Limited | Professional & scientific | 2022 |
| Memvim Healthcare Ltd | Health & social care | 2021 |
| MEN Ltd | Professional & scientific | 2018 |
| MEN Only Hairdressers Ltd | Other services | 2017 |
| Mena Commercial Limited | Real estate | 2017 |
| Mena Developments Limited Limited | Real estate | 2017 |
| Mena Residential Limited | Real estate | 2017 |
| Mena's Place Ltd | Wholesale & retail | 2017 |
| Menapia Ltd | Manufacturing | 2020 |
| Menditch Limited | Households | 1984 |
| Mendly Ltd | Information & communication | 2026 |
| Menerva Services Ltd | Health & social care | 2022 |
| Menkal Transport Ltd | Transport & logistics | 2020 |