| Moor Digital Marketing Ltd | Information & communication | 2026 |
| Moorcourt Groundcare Limited | Construction | 2020 |
| Moore Refrigeration & Air Conditioning Ltd | Construction | 2015 |
| Moorings Close Ltd | Households | 2019 |
| Moose Island Limited | Information & communication | 2007 |
| Mootress Limited | Water & waste | 2015 |
| Mopane Property Limited | Real estate | 2020 |
| Mopar Investment Holdings Limited | Real estate | 2019 |
| Mopar Logistics Ltd | Transport & logistics | 2020 |
| Mopar Ltd | Wholesale & retail | 2012 |
| MOR Enterprises Group Ltd | Construction | 2024 |
| MOR Holdings Southern Limited | Financial services | 2019 |
| Mora Advice Ltd | Administrative & support | 2015 |
| Morden Specsavers Limited | Wholesale & retail | 2005 |
| Morden Visionplus Limited | Wholesale & retail | 2005 |
| More Forward Ltd | Agriculture & fishing | 2009 |
| More Than Foil Ltd | Wholesale & retail | 2021 |
| More Than Words Design Ltd | Professional & scientific | 2022 |
| MORE4BUSINESS Limited | Administrative & support | 2022 |
| MORE4INSURE Limited | Financial services | 2023 |
| Morecambe Specsavers Limited | Wholesale & retail | 2005 |
| Morecambe Visionplus Limited | Wholesale & retail | 2005 |
| Morecare Staff Services Limited | Administrative & support | 2022 |
| Morecare Support Services Limited | Health & social care | 2008 |
| Moreland Motor Services Limited | Wholesale & retail | 2004 |
| Morgan Company Holdings Limited | Financial services | 2018 |
| Morgan Gray Associates Limited | Administrative & support | 2021 |
| Morgans Drive Management Company Ltd | Households | 2026 |
| Morhold Ltd | Real estate | 2024 |
| Morley Specsavers Hearcare Limited | Wholesale & retail | 2013 |
| Morley Specsavers Limited | Wholesale & retail | 2003 |
| Morningside Specsavers Limited | Wholesale & retail | 2008 |
| Morningside Visionplus Limited | Wholesale & retail | 2008 |
| Morpeth Specsavers Limited | Wholesale & retail | 2007 |
| Morpeth Visionplus Limited | Wholesale & retail | 2007 |
| Morris Parker Property Refurbishment Limited | Construction | 2014 |
| Morriston Specsavers Limited | Wholesale & retail | 2003 |
| Mortgage Access Ltd | Financial services | 2018 |
| Mortgage Right Kent Limited | Financial services | 2026 |
| Mortiboys Project Management Limited | Professional & scientific | 2019 |
| Mortimer Electrical Services Ltd | Construction | 2023 |
| Mosa (Winchester) Ltd | Real estate | 2023 |
| Mosselen Holdco Limited | Financial services | 2024 |
| Mothership Media Consultancy Ltd | Professional & scientific | 2024 |
| Motherwell Specsavers Limited | Wholesale & retail | 2002 |
| Motion Mechanical Services Limited | Wholesale & retail | 2025 |
| Motion Tyres Ltd | Wholesale & retail | 2024 |
| Motioncam Solutions Ltd | Administrative & support | 2025 |
| Motomex Garage Ltd | Wholesale & retail | 2017 |
| Motor MAX Ltd | Wholesale & retail | 2020 |
| Motor Vehicle NRG Limited | Wholesale & retail | 2020 |
| Motorcare Services Limited | Other services | 1991 |
| Motorcycle Workshop (Portsmouth) Limited | Wholesale & retail | 2007 |
| Motorhome Mechanic Limited | Wholesale & retail | 2023 |
| Motorsport Management Solutions Limited | Information & communication | 2016 |
| MOU Partnership Ltd | Real estate | 2023 |
| Moulded Plastic Components Ltd | Manufacturing | 2003 |
| Moulds of Petersfield Limited | Construction | 2005 |
| Movie Shaker Limited | Administrative & support | 2011 |
| Moving Oneway Limited | Professional & scientific | 2016 |
| Moxom Limited | Professional & scientific | 2020 |
| MOZ TCG Ltd | Wholesale & retail | 2025 |
| MP & JP Properties Limited | Real estate | 2023 |
| MP Heating and Plumbing Solutions Ltd | Construction | 2020 |
| MP Technical Support Services Ltd | Information & communication | 2024 |
| MPH Consult Ltd | Information & communication | 2022 |
| MPH Piling Ltd | Construction | 2025 |
| MR D&C Ltd | Wholesale & retail | 2021 |
| MR Spain Limited | Hospitality | 2014 |
| Mrcb Consulting Ltd | Information & communication | 2020 |
| MRF Estimating Ltd | Professional & scientific | 2026 |
| Mrfr Holdings Limited | Financial services | 2024 |
| Mrfr Limited | Health & social care | 2016 |
| MRR Earthmovers Limited | Professional & scientific | 2016 |
| MS Premji Limited | Health & social care | 2015 |
| Msas Services Ltd | Construction | 2015 |
| Msasa Care Limited | Health & social care | 2019 |
| MSB Electrical Northwest Limited | Construction | 2025 |
| MSC Developments (South) Limited | Real estate | 2016 |
| Msdr Consultants Limited | Information & communication | 2009 |
| Mslg Limited | Administrative & support | 2025 |
| Msmt Holding Ltd | Financial services | 2026 |
| MSN Software Solutions Ltd | Information & communication | 2022 |
| Msnet Limited | Information & communication | 2021 |
| Msps Limited | Administrative & support | 2004 |
| Mssg GAS and Electrical Services Limited | Construction | 2011 |
| Mstp Estates Limited | Real estate | 2025 |
| MT Consultancy (South) Limited | Professional & scientific | 2021 |
| MTE Electrical Services Ltd | Construction | 2023 |
| MUA Travel Ltd | Professional & scientific | 2020 |
| Mucky Bucket Farm Limited | Administrative & support | 2013 |
| Muddy Paws Dog Services Ltd | Other services | 2011 |
| MUG Shot Coffee Shop Limited | Hospitality | 2016 |
| Mulberry Close Gosport Limited | Households | 2008 |
| Mulberry Events Ltd | Hospitality | 2025 |
| Multi Quote Ltd | Financial services | 2021 |
| Multi Quote Marketing Ltd | Professional & scientific | 2023 |
| Multipix Imaging Components Limited | Information & communication | 2012 |
| Multipix Imaging Ltd | Financial services | 2019 |
| Multiple Wealth UK Co., Ltd | Wholesale & retail | 2024 |