| M Bar C Construction | San Marcos, California | Visit site |
| M&A Design Engineering | Mougins, Alpes-Maritimes | Visit site |
| M&G | London, England | Visit site |
| M&P Mechanical | Dundrum, County Dublin | Visit site |
| M+B Electrical Consulting Engineers | Calgary, Alberta | Visit site |
| M+F Technologies GmbH | Hamburg, Hamburg | Visit site |
| M+W Group | Stuttgart, Baden-Württemberg | Visit site |
| M-Spin Ltd | London, England | Visit site |
| M. J. Electric, LLC | Iron Mountain, Michigan | Visit site |
| M.C. Dean, Inc. | McLean, Virginia | Visit site |
| M.C. Electrical NY, Inc. | Yonkers, New York | Visit site |
| M.H.R. Hydraulics Limited | Brampton, Ontario | Visit site |
| M.K Tubes Industries | Moscow, Moscow | Visit site |
| M10 Solar Equipment GmbH | Freiburg im Breisgau, Baden-Württemberg | Visit site |
| M2X Energy Inc. | Bradenton, Florida | Visit site |
| MA Engineering | Bloomfield Hills, Michigan | Visit site |
| MAC Engineering and Equipment Co., Inc. | Benton Harbor, Michigan | Visit site |
| MACNY - The Manufacturers Association | Syracuse, New York | Visit site |
| MADEnR | Honfleur, Calvados | Visit site |
| MADKOUR | Cairo, Cairo | Visit site |
| MAFI Solar | Färnäs, Dalarna | Visit site |
| MAGENTA EKO | Crissier, Vaud | Visit site |
| MAK Power | Newcastle, England | Visit site |
| MAKIINA | Tampere, Pirkanmaa | Visit site |
| MAKPower | New York, New York | Visit site |
| MANERGY | Créteil, Val-de-Marne | Visit site |
| MARACOF | Granada, Granada | Visit site |
| MARS Transformers, LLC | Pearland, Texas | Visit site |
| MARTIN GmbH für Umwelt- und Energietechnik | München, Bavaria | Visit site |
| MARVAIR | Cordele, Georgia | Visit site |
| MARYLAND SOLAR SOLUTIONS, INC | Owings Mills, Maryland | Visit site |
| MBA Energy & Industrial | Magnolia, Texas | Visit site |
| MBL Energy | Stockton, California | Visit site |
| MBMET Meteorology | Kolkata, West Bengal | Visit site |
| MCE - Motion & Control Enterprises, LLC | Zelienople, Pennsylvania | Visit site |
| MCE Automation | Saint-Romain-de-Colbosc, Seine-Maritime | Visit site |
| MCH Electric, Inc. | Livermore, California | Visit site |
| MCL Construction | La Vista, Nebraska | Visit site |
| MCi Carbon | Newcastle, New South Wales | Visit site |
| MD Electrical Construction Renewables Ltd | Dartford, England | Visit site |
| MDCSystems® | Paoli, Pennsylvania | Visit site |
| MDK Energy | Praha, Prague | Visit site |
| MDP Engineering Group | Denver, Colorado | Visit site |
| MDS Power Inc. | Montréal, Quebec | Visit site |
| MEC SRL | Provaglio d'Iseo, Brescia | Visit site |
| MENRED ESS CO.,Ltd | Wenzhou Shi, Zhejiang | Visit site |
| MEP Technical Services LTD | Retford, England | Visit site |
| MEPIS | Chicago, Illinois | Visit site |
| MES Energy S.A. | Athina, Attica | Visit site |
| MESC | Washington, District of Columbia | Visit site |
| MESOGEOS S.A. | Athina, Attica | Visit site |
| METech Recycling | Gilroy, California | Visit site |
| MEYER BORGMAN JOHNSON | Minneapolis, Minnesota | Visit site |
| MFZ & Partners | Milano, Milan | Visit site |
| MGD Energy SA | Amarousio, Attica | Visit site |
| MGE COMPANIES (MG Engineering, MGE Unified Technologies, MGE Lighting Design Collaborative) | New York, New York | Visit site |
| MGM Projekt Sp. z o.o. | Katowice, Silesian Voivodeship | Visit site |
| MGM Transformers | Commerce, California | Visit site |
| MHI Vestas Offshore Wind | Aarhus, Central Denmark | Visit site |
| MICC Manufacturing Corporation | Bowling Green, Ohio | Visit site |
| MILLER BROS. | Conshohocken, Pennsylvania | Visit site |
| MILPLAN Engenharia | Belo Horizonte, Minas Gerais | Visit site |
| MINITRUCKS ROBOTICS | Vénissieux, Rhône | Visit site |
| MINT SA | Montpellier, Hérault | Visit site |
| MIP ENGENHARIA | Belo Horizonte, Minas Gerais | Visit site |
| MITRE | McLean, Virginia | Visit site |
| MITSCN | Beijing, Beijing | Visit site |
| MK Battery | Albuquerque, New Mexico | Visit site |
| MK Surveys | Milton Keynes, England | Visit site |
| MKM Building Group | Ballarat, Victoria | Visit site |
| MLEI Consulting Engineers | Adelaide, South Australia | Visit site |
| MLN Company | Stafford, Texas | Visit site |
| MMD Solar | California | Visit site |
| MMR Energie | Ranstadt, Hesse | Visit site |
| MMR Group | Baton Rouge, Louisiana | Visit site |
| MMSA | Singapore, Central Singapore Community Development Council | Visit site |
| MN projects GmbH | Hamburg, Hamburg | Visit site |
| MNG | Perth, Western Australia | Visit site |
| MNS Consulting IL | Illinois | Visit site |
| MONDRAGON Corporation | Basque Country | Visit site |
| MOREDAY SOLAR | Ningbo Shi, Zhejiang | Visit site |
| MOTOMA SOLAR ENERGY CO. LLC | Dongwan Shi, Guangdong | Visit site |
| MOTORTECH GmbH | Celle, Lower Saxony | Visit site |
| MP Systems Inc. | New Berlin, Wisconsin | Visit site |
| MPE Consulting | Mechanical + Electrical + Plumbing + Lighting | San Diego, California | Visit site |
| MPMC | Harrisburg, Pennsylvania | Visit site |
| MRCOOL | Paducah, Kentucky | Visit site |
| MS Directional | Conroe, Texas | Visit site |
| MS GALLEON Group | Vienna, Missouri | Visit site |
| MSCI Carbon Markets | London, England | Visit site |
| MSS Steel Tubes | Bente, Braga | Visit site |
| MSite by Infobric | Liverpool, England | Visit site |
| MSquare Energy | New South Wales | Visit site |
| MT Solar | Charlo, Montana | Visit site |
| MTC ENERJİ | Çankaya, Ankara | Visit site |
| MTM Engineering Ltd | Painestown, Meath | Visit site |
| MULTICOPER SRL | Parre, Bergamo | Visit site |
| MWA Technology Ltd | Birmingham, England | Visit site |
| MWB Engineering | New York, New York | Visit site |
| MYR Group | Thornton, Colorado | Visit site |
| MYROPES | Olkusz, Lesser Poland Voivodeship | Visit site |
| MaC Venture Capital | Los Angeles, California | Visit site |
| MaRS Discovery District | Toronto, Ontario | Visit site |
| Mac Zero Modular Buildings | Dungannon, Northern Ireland | Visit site |
| Mace | London, England | Visit site |
| Machine Tools Centre | Kolkata, West Bengal | Visit site |
| Mack Kirk Industries Ltd | Langley, British Columbia | Visit site |
| Mackay Communications, Inc. | Raleigh, North Carolina | Visit site |
| Macon Power | Albany, Georgia | Visit site |
| Macquarie Group | Sydney, New South Wales | Visit site |
| Macrotek Inc. | Markham, Ontario | Visit site |
| Macwin Solar | Surat, Gujarat | Visit site |
| Maddox Industrial Transformer | Greer, South Carolina | Visit site |
| Magenta Mobility | Navi Mumbai, Maharashtra | Visit site |
| MagicPower | 新北市, New Taipei City | Visit site |
| Magid | Romeoville, IL | Visit site |
| Magnatic | Bengaluru, Karnataka | Visit site |
| Magnum Energy | Saint Paul, Minnesota | Visit site |
| Magnum Piering | Springdale, Ohio | Visit site |
| Magtel | Córdoba, Córdoba | Visit site |
| Main Stream Electric | San Jose, California | Visit site |
| Maine Governor's Energy Office | Indianapolis, Indiana | Visit site |
| Mainspring Energy | Menlo Park, California | Visit site |
| Majorpower Corporation | Mebane, North Carolina | Visit site |
| Makintest Teknik Muayene Ölçüm ve Gözetim Hizmetleri | Sancaktepe, Istanbul | Visit site |
| Malaviya Solar Energy Consultancy | Pune, Maharashtra | Visit site |
| Malcolm Drilling | San Francisco, California | Visit site |
| Malk Partners | New York, New York | Visit site |
| Mana Monitoring | Lahaina, Hawaii | Visit site |
| Manawa Energy | Tauranga, Bay of Plenty | Visit site |
| Mantel | Cambridge, Massachusetts | Visit site |
| Maodi Solar | Shenzhen Shi, Guangdong | Visit site |
| Mapmatic Ltd | Derby, England | Visit site |
| Mar-Bal, Inc | Chagrin Falls, Ohio | Visit site |
| Marathon Petroleum Corporation | Findlay, Ohio | Visit site |
| Marcellus Shale Coalition | Pittsburgh, Pennsylvania | Visit site |
| Marco Group Limited | St. John's, Newfoundland and Labrador | Visit site |
| Mardi Engineering | Vero Beach, Florida | Visit site |
| Maretron | Jupiter, Florida | Visit site |
| Marimón Abogados | Madrid | Visit site |
| Marine Renewables Canada | Halifax, Nova Scotia | Visit site |
| Mark III Construction, Inc. | Sacramento, California | Visit site |
| Marking Services Incorporated | Milwaukee, Wisconsin | Visit site |
| Marmon Utility | Milford, New Hampshire | Visit site |
| Marny Energy | Villeurbanne, Rhône | Visit site |
| Marquis Solar Frameworks | Stoughton, Wisconsin | Visit site |
| Marstek Energy Co.,Limited | Shenzhen Shi, Guangdong | Visit site |
| Marti Group | Moosseedorf, Bern | Visit site |
| Martin AG für Umwelt- und Energietechnik | Wettingen, Aargau | Visit site |
| Martin Solar | Mascoutah, IL | Visit site |