| Mana Healthcare Ltd | Barnsley | 2025 |
| Manage Care Limited | Willenhall | 2019 |
| Manageflow Systems Ltd | Liverpool | 2023 |
| Management & Training Corporation Limited | London | 2014 |
| Manajoy Ltd | Milton Keynes | 2023 |
| Manchester DRY Risers Ltd | Bolton | 2025 |
| Manchester Fire Marshals Ltd | Stockport | 2023 |
| Manchester Investment and Development Agency Service Limited | Manchester | 1997 |
| Manchester Respiratory Care Limited | Altrincham | 2024 |
| Manchester Security Fencing Ltd | Manchester | 2016 |
| Mandala 2016 Ltd | Woodford Green | 2016 |
| Mandate Healthcare Ltd | Aylesbury | 2022 |
| Mane K9 Security Services Ltd | Hockley | 2018 |
| MANGXONGO64 Limited | Manchester | 2023 |
| Manila Outstanding Care Ltd | London | 2025 |
| Manilla Support Services Ltd | Northampton | 2024 |
| Manjang Care Limited | London | 2024 |
| Manju Trading Company Ltd | Leeds | 2020 |
| Mankobo Enterprises Limited | Dartford | 2023 |
| Mann TAN Ltd | Edgware | 2019 |
| Manna House Health Education & Wellness Community Interest Company | Stone | 2019 |
| Manor Hall Specialist Care Partnerships Limited | Stirlingshire | 2013 |
| Manor Mill (UK) Ltd | Totnes | 2012 |
| Manse Secretarial Services Limited | Wootton Bridge | 2011 |
| Mansfield Fire & Electrical (Engineers) Ltd | Mansfield | 2017 |
| Mansfield Fire Protection Group Ltd | Wooburn Green | 2024 |
| Mansory Maintenance Ltd | Doncaster | 2024 |
| Manta Fire Limited | Stoke On Trent | 2025 |
| Mantlet Consulting Limited | Dorchester | 2017 |
| Maprel and Co Ltd | Bolton | 2020 |
| Maprie Bhebhe Limited | Dewsbury | 2025 |
| Maps Defence Global Ltd | Kidderminster | 2020 |
| Maps Defence Ltd | Kidderminster | 2020 |
| MAR Business Coaching Limited | Taunton | 2021 |
| Marabim Limited | Woodford Green | 2022 |
| Marb Construction Limited | London | 2014 |
| Marco - Your Mobile Physio Ltd | London | 2025 |
| Marcurius Ltd | London | 2025 |
| Marcusmarc Ltd | Aylesbury | 2023 |
| Maria Merlas Limited | Swansea | 2023 |
| Maria Rasul Ltd | Cheadle | 2020 |
| Mariaglauro Ltd | London | 2024 |
| Mariam Locum Services Ltd | London | 2025 |
| Marie Assessments Limited | Watford | 2024 |
| Marin Associates Limited | Cardiff | 2013 |
| Maritime Fire Safety Ltd | Preston | 2024 |
| Marjesi Health Care Ltd | London | 2025 |
| Mark 1 Fire Solutions Limited | Stockport | 2021 |
| Mark Communications Limited | London | 2018 |
| Mark Edward Stanforth Ltd | Kingswinford | 2026 |
| Mark Kane Fire Door Audit Ltd | Solihull | 2025 |
| Markdanjomic Ltd | London | 2020 |
| Markfire Ltd. | Coventry | 2014 |
| Markwell Consulting Ltd | Cambridge | 2024 |
| Marpan Healthcare Ltd | St. Neots | 2022 |
| Marsh Care Ltd | Salford | 2020 |
| Marshall K9 Ltd | London | 2025 |
| Marshall TM Ltd | Banbury | 2025 |
| Marshalls Fire Protection Ltd | Gillingham | 2019 |
| Marston Medical Consulting Ltd | Thames Ditton | 2026 |
| Marston Resources Limited | London | 2012 |
| Martin Ball Communications Limited | London | 2016 |
| Martin Phelps Systems Ltd | Cirencester | 2005 |
| Martin's Electric Services Limited | Bourne End | 2009 |
| Martyn Young Fire Proofing Consultancy Ltd | Stroud | 2019 |
| Maru Enterprise CIC | London | 2025 |
| Marula Support Services Ltd | Birmingham | 2024 |
| Marvin - Charles Elevate Group Ltd | Tondu | 2018 |
| Mary DH Services Ltd | London | 2025 |
| Maryam Fire Safety Ltd | Chigwell | 2012 |
| Maryam Medical Limited | Manchester | 2025 |
| Marykam Limited | Walsall | 2025 |
| MAS Fire Sure Consultancy Ltd | Derby | 2026 |
| MAS Zengrange Limited | St Albans | 1995 |
| Masami Ltd | Matlock | 2018 |
| Maslow Mental Health Group Ltd | Lisburn | 2021 |
| Mason Media Ltd | Chester | 2003 |
| Mass Heating Services Ltd | Northampton | 2018 |
| MAT Fire Protection Ltd | Grays | 2025 |
| MAT24 Care Limited | St. Helens | 2018 |
| Mathe Ltd | Glasgow | 2018 |
| Mathews Medical Ltd | Birmingham | 2018 |
| Matrescence Village Ltd | London | 2025 |
| Matrix Fire Alarms Ltd | Basildon | 2011 |
| Matt Ottaway Contracting Ltd | Buckingham | 2023 |
| Mattdora Health & Social Care Limited | Nottingham | 2024 |
| Matteo Sprinkler Systems Ltd | Barking | 2024 |
| Matthew Brown Consulting Ltd | London | 2026 |
| Matthew Joseph Consultancy Ltd | Upminster | 2015 |
| Matthew Orrick TM Ltd | Wallsend | 2023 |
| Matthews Medicolegal Expert Witness Services Ltd | Sunderland | 2021 |
| Matz Care Services Limited | Grays | 2022 |
| Maud Ltd | Tadley | 2023 |
| Maun Fire Safety Limited | Mansfield | 2017 |
| Maureen Carson Health Executive Consultancy Limited | Norwich | 2013 |
| Maurel House Ltd | Swindon | 2025 |
| Maurice Johnson & Partners UK Limited | Leamington Spa | 2024 |
| Mausuk Ltd | Nottingham | 2024 |
| Mauve Ventures Company Limited | London | 2026 |
| MAV FSA Limited | Plymouth | 2026 |