| Linda & Matt Ltd | Construction | 2019 |
| Linpep Limited | Real estate | 2019 |
| Lion Heritage Ltd | Construction | 2022 |
| Little Angel (Whitby) Limited | Hospitality | 2011 |
| Little Angel Apparel Limited | Wholesale & retail | 2025 |
| Little Bird Solutions Limited | Information & communication | 2015 |
| Little Rainbows (Whitby) Limited | Health & social care | 2019 |
| Little Teapots Nursery Ltd | Health & social care | 2022 |
| LMD Weddings Limited | Information & communication | 2024 |
| Lockers Trawlers Limited | Agriculture & fishing | 1987 |
| Longstone Holiday Cottages Ltd | Hospitality | 2005 |
| Lopanesque Translation Services Limited | Professional & scientific | 2017 |
| Love Cottage Getaways Ltd | Real estate | 2024 |
| Love My Dress (UK) Limited | Information & communication | 2014 |
| LOW Quebec Limited | Information & communication | 2025 |
| LOW Whinns Limited | Agriculture & fishing | 2011 |
| Lowfield Construction Services Ltd | Professional & scientific | 2021 |
| Loxley Solutions Ltd | Manufacturing | 2018 |
| LTC Electrical Services Limited | Construction | 2016 |
| Lucky House Whitby Limited | Hospitality | 2024 |
| Lupine Cottage Ltd | Real estate | 2025 |
| Lythe Village Hall Trustee Limited | Other services | 2009 |
| M & J RIG Services Ltd | Mining & quarrying | 2017 |
| M & M Motors (Egton) Limited | Wholesale & retail | 2003 |
| M&T Commercials Limited | Wholesale & retail | 2018 |
| Macaw Media Limited | Information & communication | 2016 |
| Macaw Rentals Ltd | Real estate | 2026 |
| Macellies Properties Limited | Real estate | 2021 |
| MAD Marys Limited | Hospitality | 2022 |
| Maddox Advisory Limited | Information & communication | 2015 |
| Made in Whitby Ltd | Other services | 2023 |
| Madjak Associates Limited | Professional & scientific | 2010 |
| Malkin House Ltd | Hospitality | 2021 |
| Maple Associates (Recruitment) Limited | Professional & scientific | 1986 |
| Marie Antoinette's Patisserie Ltd | Wholesale & retail | 2018 |
| Marina View (Whitby) Limited | Households | 1990 |
| Marine Discovery Centre Whitby CIC | Agriculture & fishing | 2022 |
| Marisco (Whitby) Limited | Wholesale & retail | 2005 |
| Maritom Limited | Financial services | 2023 |
| Mark Stringer Building Limited | Construction | 2000 |
| Marketing Matters Ltd | Professional & scientific | 2020 |
| Marspec Engine Consultants Ltd | Professional & scientific | 2006 |
| Martin Holland Limited | Health & social care | 2019 |
| Martyn Cana Building & Roofing Ltd | Construction | 2021 |
| MARWEST25 Ltd | Hospitality | 2025 |
| Mary's Sandwich Shop Limited | Hospitality | 2023 |
| Matthew Thackray D.S. Ltd | Professional & scientific | 1994 |
| Maxfield Minerals Limited | Administrative & support | 2017 |
| MB Mechanical Services (Whitby) Limited | Extraterritorial | 2014 |
| MC Electrical and Sons Limited | Construction | 2016 |
| Meadowcroft Ugthorpe Ltd | Education | 2018 |
| Mediability AG Limited | Professional & scientific | 2011 |
| Mediability DMG Limited | Professional & scientific | 2011 |
| MEL P Inspection Limited | Professional & scientific | 2011 |
| MET Leisure Limited | Hospitality | 2017 |
| Metropole Association Limited | Households | 2013 |
| MHA PR Ltd | Professional & scientific | 2018 |
| Mike Dowson Limited | Administrative & support | 1997 |
| Mike Hogarth Limited | Construction | 2001 |
| Mike Sutton Property Services Limited | Real estate | 2025 |
| Mike Tindall Ltd | Administrative & support | 2023 |
| Mikest Limited | Transport & logistics | 2018 |
| Mikjulora Dobermanns Limited | Agriculture & fishing | 2018 |
| Milan Works Limited | Real estate | 2019 |
| Miller Financial Solutions Ltd | Financial services | 2018 |
| Milward Properties Limited | Hospitality | 1991 |
| Mind Over Moors Ltd | Arts & recreation | 2026 |
| Mindello Apartments Limited | Real estate | 2016 |
| Mirrorbox Ltd | Professional & scientific | 2021 |
| Mister Chips by the Beach Limited | Hospitality | 2018 |
| Mister Chips Holdings Limited | Hospitality | 2002 |
| Mister Chips Limited | Hospitality | 2018 |
| Mister Chips Property Limited | Real estate | 2015 |
| Mistress Sea Angling Charters Ltd | Transport & logistics | 2012 |
| Mitre (Glaisdale) Management Limited | Real estate | 2008 |
| Mitten Hill Minerals Ltd | Mining & quarrying | 2012 |
| MJ Landscaping Services Limited | Administrative & support | 2021 |
| Mjbg Mozzas | Financial services | 2025 |
| MJC Scaffolding Solutions Ltd | Construction | 2025 |
| MJL Mickley Ltd | Professional & scientific | 2012 |
| Mjmr Limited | Mining & quarrying | 2012 |
| MJT Trading Ltd | Hospitality | 2022 |
| Mkelly Trading Ltd | Financial services | 2026 |
| MLW Access Solutions Ltd | Construction | 2026 |
| MML & V Limited | Professional & scientific | 2012 |
| Modern Mint Ltd | Administrative & support | 2014 |
| Monkey Puzzle Brew Co Ltd | Manufacturing | 2022 |
| Monks Haven Whitby Limited | Hospitality | 2012 |
| Montmartre (Whitby) Ltd | Hospitality | 2022 |
| Moor & Tide Limited | Wholesale & retail | 2015 |
| Moor and Coast Care Limited | Health & social care | 2017 |
| Moor Croft Glamping Ltd | Other services | 2021 |
| Moorland & Meadow Restoration Limited | Agriculture & fishing | 2006 |
| Moors Traffic Signals Limited | Administrative & support | 2017 |
| Morados Drinks Limited | Manufacturing | 2025 |
| Morhyde Limited | Administrative & support | 2013 |
| Moutreys Yorkshire Ltd | Hospitality | 2024 |
| MPH Agricultural Services Limited | Administrative & support | 2019 |
| Mpktc Limited | Hospitality | 2015 |
| MR Blue Whitby Limited | Wholesale & retail | 2026 |