| Mmiucy Co., Ltd | Wholesale & retail | 2023 |
| MMN Electrical Solutions Ltd | Construction | 2021 |
| MNR Contract Services Ltd | Construction | 2024 |
| MO Fades Barbers Ltd | Other services | 2024 |
| MO H&S Ltd | Professional & scientific | 2024 |
| Mobile Masters Ponty Ltd | Other services | 2026 |
| Mobimi Games Ltd | Information & communication | 2017 |
| Moisons Creative Cafe Ltd | Hospitality | 2026 |
| Moisons Holdings Limited | Real estate | 2026 |
| Moisons Management Consultants Limited | Professional & scientific | 2013 |
| Mojak Utilities Ltd | Construction | 2015 |
| Molly After Midnight CIC | Information & communication | 2025 |
| Molly O`Ds Limited | Hospitality | 2007 |
| Moonbeam Beauty Studio Ltd | Other services | 2021 |
| MOR Training (Commercial) Ltd | Education | 2004 |
| MOR Training Ltd | Education | 2006 |
| Morg Techco CYF | Administrative & support | 2025 |
| Morgan Bailey Homes Limited | Real estate | 2019 |
| Mosaic Leadership Ltd | Professional & scientific | 2020 |
| Motohaus Limited | Wholesale & retail | 2019 |
| Motorsense South Wales Ltd | Wholesale & retail | 2021 |
| MP Carpentry Limited | Construction | 2019 |
| MRG Finance Group Ltd | Financial services | 2019 |
| MRG Management Ltd | Professional & scientific | 2019 |
| MS Autos Pontypridd Ltd | Wholesale & retail | 2024 |
| Msarb Limited | Agriculture & fishing | 2020 |
| MSC Construction Limited | Construction | 2011 |
| MSF Group Ltd | Health & social care | 2020 |
| MSP - Lettings & Property Limited | Construction | 2023 |
| MST Sports Ltd | Other services | 2015 |
| MT Properties (South Wales) Limited | Real estate | 2018 |
| MTH Heating Limited | Construction | 2011 |
| Mudassir Bhatti Ltd | Wholesale & retail | 2025 |
| Multea Choice Treforest Ltd | Wholesale & retail | 2025 |
| Multi Choice Plumbing Ltd | Construction | 2023 |
| Multi Heat Ltd | Construction | 2025 |
| Multi-Heat Services Ltd | Construction | 2011 |
| Multiversity Enterprise Ltd | Wholesale & retail | 2019 |
| Mummy TEE Limited | Wholesale & retail | 2024 |
| Munis Contractors Ltd | Administrative & support | 2018 |
| Murph's and Bulk Ltd | Wholesale & retail | 2025 |
| MV Safeguarding and Investigations Ltd | Administrative & support | 2022 |
| MWS Rail Ltd | Construction | 2024 |
| Mylockme Fashion Company Ltd | Wholesale & retail | 2025 |
| Mynachdy Limited | Arts & recreation | 2019 |
| N & K Barbers Ltd | Other services | 2022 |
| N J Chips & Scuffs Limited | Other services | 2014 |
| N J M T Properties Ltd | Real estate | 2024 |
| Naetive Limited | Manufacturing | 2023 |
| Nano-Sepmer Membrane Technology Ltd. | Professional & scientific | 2020 |
| Nant Holdings Limited | Financial services | 2020 |
| Nathan Ellis Designs Limited | Professional & scientific | 2017 |
| Nathan Rhys Wyle Ltd | Education | 2025 |
| Nathan Wyle Ltd | Construction | 2019 |
| Nathfloy Consult UK Ltd | Professional & scientific | 2025 |
| Nation Clan Limited | Financial services | 2026 |
| Natty's Delicatessen Limited | Wholesale & retail | 2025 |
| Natural Twenty Ltd | Information & communication | 2019 |
| Naturally for Pets Ltd | Agriculture & fishing | 2023 |
| Naturescape Maintenance Ltd | Administrative & support | 2025 |
| NCF Global Limited | Wholesale & retail | 2025 |
| Near ME NOW Ltd | Information & communication | 2016 |
| Neath DC Ltd | Health & social care | 2026 |
| Neccovocreationslondon Ltd | Wholesale & retail | 2024 |
| Neil Broadstock Limited | Administrative & support | 2016 |
| Neil Cross Formwork and Construction Services Limited | Construction | 2021 |
| Nemarain Limited | Wholesale & retail | 2025 |
| Neon Nights - Skate-O-Rama CIC | Arts & recreation | 2025 |
| New Culture Coffee Ltd | Hospitality | 2026 |
| New Rickards Arms Ltd | Hospitality | 2026 |
| New Start Financial Solutions Ltd | Professional & scientific | 2010 |
| NEW2WIN Fitness Ltd | Education | 2024 |
| NEWHOUSEMOTORS2011 Limited | Wholesale & retail | 2011 |
| Newregyu Limited | Manufacturing | 2023 |
| Newstar Global E-Commerce Co., Ltd. | Wholesale & retail | 2026 |
| Nexa Southwest Limited | Real estate | 2020 |
| Nexadigital.Group Ltd | Information & communication | 2026 |
| Nexjen Interiors Limited | Construction | 2019 |
| Next Generation Property Group Ltd | Real estate | 2022 |
| NFC Comms Limited | Professional & scientific | 2018 |
| NFC Global Limited | Wholesale & retail | 2025 |
| NG Wholesale Limited | Wholesale & retail | 2025 |
| NHO Limited | Health & social care | 2016 |
| Nice Tech Group Limited | Manufacturing | 2026 |
| Nicholas Craig Logistics Limited | Transport & logistics | 2019 |
| Nick&George Ltd | Hospitality | 2025 |
| Nico POD Bros Limited | Wholesale & retail | 2025 |
| Nicola Downie Florist Ltd | Wholesale & retail | 2019 |
| Nidan Management Services Limited | Professional & scientific | 1980 |
| NIG KIT Holdings Limited | Financial services | 2024 |
| NIG MAR Holdings Ltd | Financial services | 2017 |
| Nila Retail Ltd | Wholesale & retail | 2023 |
| Ningbo Fameway Corporation Ltd. | Wholesale & retail | 2009 |
| Ningbo Wellecos Stationery & Gift Co., Ltd | Extraterritorial | 2017 |
| Ningbo Yinanqi Technology Company Limited | Wholesale & retail | 2026 |
| Ningbo Zshine Leisure Industry Co., Ltd. | Extraterritorial | 2021 |
| NIX and Nice Limited | Health & social care | 2024 |
| NJB Events Ltd | Arts & recreation | 2017 |
| NLS Evans Ltd | Real estate | 2018 |
| NM Construction Management Ltd | Construction | 2025 |