| Ktech Group Limited | Construction | 2015 |
| Kwik Lets Limited | Real estate | 1990 |
| L Brown Construction Limited | Construction | 2013 |
| Lady of the Forest Limited | Construction | 2023 |
| Landstone Group Limited | Financial services | 2023 |
| Lasmore Limited | Professional & scientific | 2019 |
| Layla's Magic Store Ltd | Other services | 2026 |
| LEE Fisher Trading Ltd | Real estate | 2024 |
| Let's GET Talking LLP | | 2012 |
| Let's Go (Consulting) Ltd | Administrative & support | 2013 |
| Leyswood Limited | Professional & scientific | 2008 |
| Lfai Limited | Health & social care | 2025 |
| Liam Joyce Limited | Construction | 2017 |
| Liam White Ltd | Professional & scientific | 2019 |
| Living Room Circus Ltd | Arts & recreation | 2018 |
| LK Corporate Consultancy Limited | Professional & scientific | 2023 |
| Local Sustainable CIC | Agriculture & fishing | 2020 |
| Logistics Operations Limited | Transport & logistics | 2006 |
| London & Thames Counties Securities Limited | Professional & scientific | 1971 |
| London Car Charger Limited | Extraterritorial | 2023 |
| London Sights Limited | Arts & recreation | 2010 |
| Long Run Works Limited | Professional & scientific | 2014 |
| Longman Canine Academy Ltd | Wholesale & retail | 2026 |
| Lucas Brown Racing Ltd | Professional & scientific | 2023 |
| Lucian Camp Consulting Limited | Professional & scientific | 2009 |
| Luke Edkins Limited | Construction | 2014 |
| Luxford Homes Limited | Construction | 2022 |
| Lyme Bay Consulting Limited | Professional & scientific | 2013 |
| M J Kloss Carpentry and Joinery Limited | Construction | 2024 |
| M W Vehicle Engineers Ltd | Wholesale & retail | 2010 |
| Manor House (Forest ROW) RTM Company Limited | Households | 2020 |
| Marcos Properties Ltd | Real estate | 2017 |
| Marey Ltd | Manufacturing | 2020 |
| Mark Morris Consulting Limited | Professional & scientific | 2023 |
| Martin’S Construction and Carpentry Ltd | Construction | 2023 |
| Martyn Cremin Professional Legal Services Limited | Professional & scientific | 2021 |
| Mason Rose Private Limited | Administrative & support | 2008 |
| Maurice Rodwell Limited | Construction | 1953 |
| Mcgloin Services Ltd | Professional & scientific | 2014 |
| Medber Investments Limited | Construction | 1963 |
| Medical Moves Limited | Transport & logistics | 2009 |
| Metope Studio Ltd | Administrative & support | 2021 |
| Michael Grice Developments Limited | Real estate | 1978 |
| Mid-Sussex Timber Co Limited | Wholesale & retail | 1947 |
| Mill Lane Asset Management (Croydon) Limited | Real estate | 2015 |
| Milton's Plumbing and Heating Ltd | Construction | 2022 |
| Mindful Consultancy Ltd | Health & social care | 2019 |
| Mineral Resources International (UK) Limited | Health & social care | 1998 |
| Miss MAI Ltd | Professional & scientific | 2013 |
| MLW Property Management Ltd | Real estate | 2024 |
| Mojet Ventilation Ltd | Professional & scientific | 2025 |
| Mojo Orthotic Limited | Professional & scientific | 2011 |
| Molly M Limited | Wholesale & retail | 2015 |
| Molly Mahon Limited | Wholesale & retail | 2017 |
| Montford Road Limited | Real estate | 2024 |
| Mook Ltd | Education | 2015 |
| Moor Spa International Limited | Wholesale & retail | 2000 |
| More MPG NOW Limited | Professional & scientific | 2009 |
| Morebridge Investments Limited | Financial services | 2019 |
| Morris Minor Centre (Bath) Limited | Wholesale & retail | 1981 |
| Mosen Limited | Professional & scientific | 2007 |
| Moving Image Films Limited | Professional & scientific | 2008 |
| MS FIX Limited | Other services | 2021 |
| Mtnr Tech Ltd | Information & communication | 2024 |
| Much Shorter Limited | Professional & scientific | 2004 |
| N-Trusted Ltd | Administrative & support | 2012 |
| N.B. Plant Hire Limited | Administrative & support | 1973 |
| Nankawa Clayton Limited | Wholesale & retail | 2017 |
| Naturalistic Blessing Limited | Other services | 2022 |
| Nature Provides Ltd. | Manufacturing | 2017 |
| Natureways-Therapy C.I.C. | Health & social care | 2022 |
| Nefta Developments Limited | Information & communication | 2022 |
| Nefta Group Limited | Information & communication | 2022 |
| Nela Willis Limited | Professional & scientific | 2003 |
| Newgale Farm Cottages Limited | Real estate | 2020 |
| Newmans-Services Limited | Administrative & support | 2017 |
| Nezora Ltd | Information & communication | 2025 |
| Nicolas Pople Architects Ltd | Professional & scientific | 2013 |
| NOA Adam Homeopathy Ltd | Health & social care | 2023 |
| Norley Limited | Construction | 1980 |
| Nutrigx Limited | Health & social care | 2018 |
| Oast Kits Ltd | Wholesale & retail | 2023 |
| Obsidian 99262 Limited | Professional & scientific | 2002 |
| Ocean View House (Sussex) Ltd | Real estate | 2024 |
| Ohmg Brands Limited | Manufacturing | 2020 |
| Olli Cunningham Limited | Education | 2013 |
| Olumina Limited | Information & communication | 2025 |
| OLW Project Services Ltd | Construction | 2025 |
| Omer Knaz Photography Limited | Professional & scientific | 2011 |
| ON My Side | Hospitality | 2011 |
| Oncology Imaging Systems Limited | Wholesale & retail | 1999 |
| One the Square Limited | Arts & recreation | 2014 |
| Open FD Ltd | Construction | 2023 |
| Optimum Partners Limited | Real estate | 2025 |
| Orange Aero Holdings Limited | Professional & scientific | 2015 |
| Orpen Limited | Construction | 2011 |
| OT 4 U Limited | Health & social care | 2015 |
| OYO Land Management (Thame) Limited | Real estate | 2005 |
| P Joli Limited | Wholesale & retail | 2022 |
| PAC Corporate Ltd | Hospitality | 2009 |