| # | Company name | Role | # of projects |
|---|---|---|---|
| 21 | ME Engineers | MEP engineering | 0 |
| 22 | ME Engineers | MEP engineering | 1 |
| 23 | Meco Engineering Limited | MEP engineering | 1 |
| 24 | Mehandes Engineering, P.C. | MEP engineering | 9 |
| 25 | MEIT Associates | MEP engineering | 2 |
| 26 | Mellardi | MEP engineering | 1 |
| 27 | Melvin Cohen & Associates | MEP engineering | 13 |
| 28 | Menasco Mechanical Contracting (L.L.C.) | MEP engineering | 2 |
| 29 | Menorah Group - Izu Aharon Ltd. | MEP engineering | 1 |
| 30 | Mera Technik Sp. z o.o. | MEP engineering | 3 |
| 31 | Merker AG | MEP engineering | 1 |
| 32 | Metropolitan Engineering, Inc./Shapiro-O'Brien | MEP engineering | 8 |
| 33 | Mey Arad | MEP engineering | 4 |
| 34 | Meyers+ Engineers | MEP engineering | 4 |
| 35 | Michael D. Muray, PE | MEP engineering | 1 |
| 36 | Michael E. James & Associates, Inc. | MEP engineering | 2 |
| 37 | Michaud Cooley Erickson | MEP engineering | 33 |
| 38 | Michaud, Cooley, Hallberg, Erickson & Associates | MEP engineering | 11 |
| 39 | Miller Building Corporation | MEP engineering | 2 |
| 40 | Mitsubishi Heavy Industries, Ltd. | MEP engineering | 9 |