| # | Company name | Role | # of projects |
|---|---|---|---|
| 421 | M-E Engineers | MEP engineering | 5 |
| 422 | M-Engineering, Inc. | MEP engineering | 5 |
| 423 | M.E. Group, Inc. | MEP engineering | 4 |
| 424 | M.V. Shore Associates Ltd. | MEP engineering | 107 |
| 425 | M&E Consulting, Inc. | MEP engineering | 18 |
| 426 | MacArdle McSweeney Associates | MEP engineering | 1 |
| 427 | MacCormack Associates Consultants Pty Ltd | MEP engineering | 2 |
| 428 | Malone Finkle Eckhardt & Collins, Inc. | MEP engineering | 12 |
| 429 | MAPCO LLC | MEP engineering | 5 |
| 430 | Marino Gerazounis & Jaffe Associates, Inc. | MEP engineering | 16 |
| 431 | Marten, Nagy, Tonella Associates, Inc. | MEP engineering | 1 |
| 432 | Mashayekhi Consultants, Inc. | MEP engineering | 1 |
| 433 | Maygmo | MEP engineering | 0 |
| 434 | McGuire Engineers | MEP engineering | 4 |
| 435 | McKenney's, Inc. | MEP engineering | 28 |
| 436 | MCW Consultants Ltd. | MEP engineering | 54 |
| 437 | MDJ Montagens | MEP engineering | 15 |
| 438 | ME Engineers | MEP engineering | 0 |
| 439 | ME Engineers | MEP engineering | 1 |
| 440 | Meco Engineering Limited | MEP engineering | 1 |