| Macclesfield | Tim Roca | Labour | 4 July 2024 |
| Maidenhead | Mr Joshua Reynolds | Liberal Democrat | 4 July 2024 |
| Maidstone and Malling | Helen Grant | Conservative | 6 May 2010 |
| Makerfield | Andy Burnham | Labour (Co-op) | 18 June 2026 |
| Maldon | Sir John Whittingdale | Conservative | 9 April 1992 |
| Manchester Central | Lucy Powell | Labour (Co-op) | 15 November 2012 |
| Manchester Rusholme | Afzal Khan | Labour | 8 June 2017 |
| Manchester Withington | Jeff Smith | Labour | 7 May 2015 |
| Mansfield | Steve Yemm | Labour | 4 July 2024 |
| Melksham and Devizes | Brian Mathew | Liberal Democrat | 4 July 2024 |
| Melton and Syston | Edward Argar | Conservative | 7 May 2015 |
| Meriden and Solihull East | Saqib Bhatti | Conservative | 12 December 2019 |
| Merthyr Tydfil and Aberdare | Gerald Jones | Labour | 7 May 2015 |
| Mid and South Pembrokeshire | Henry Tufnell | Labour | 4 July 2024 |
| Mid Bedfordshire | Blake Stephenson | Conservative | 4 July 2024 |
| Mid Buckinghamshire | Greg Smith | Conservative | 12 December 2019 |
| Mid Cheshire | Andrew Cooper | Labour | 4 July 2024 |
| Mid Derbyshire | Jonathan Davies | Labour | 4 July 2024 |
| Mid Dorset and North Poole | Vikki Slade | Liberal Democrat | 4 July 2024 |
| Mid Dunbartonshire | Susan Murray | Liberal Democrat | 4 July 2024 |
| Mid Leicestershire | Mr Peter Bedford | Conservative | 4 July 2024 |
| Mid Norfolk | George Freeman | Conservative | 6 May 2010 |
| Mid Sussex | Alison Bennett | Liberal Democrat | 4 July 2024 |
| Mid Ulster | Mr Cathal Mallaghan | Sinn Féin | 4 July 2024 |
| Middlesbrough and Thornaby East | Andy McDonald | Labour | 29 November 2012 |
| Middlesbrough South and East Cleveland | Luke Myer | Labour | 4 July 2024 |
| Midlothian | Kirsty McNeill | Labour (Co-op) | 4 July 2024 |
| Milton Keynes Central | Emily Darlington | Labour | 4 July 2024 |
| Milton Keynes North | Chris Curtis | Labour | 4 July 2024 |
| Mitcham and Morden | Dame Siobhain McDonagh | Labour | 1 May 1997 |
| Monmouthshire | Catherine Fookes | Labour | 4 July 2024 |
| Montgomeryshire and Glyndŵr | Steve Witherden | Labour | 4 July 2024 |
| Moray West, Nairn and Strathspey | Graham Leadbitter | Scottish National Party | 4 July 2024 |
| Morecambe and Lunesdale | Lizzi Collinge | Labour | 4 July 2024 |
| Motherwell, Wishaw and Carluke | Pamela Nash | Labour | 4 July 2024 |