| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | M Environmental & Engineering Inc | Consultancy | 1 |
| 2 | M L Rongo Inc. | Consultancy | 0 |
| 3 | M Trummel & Associates | Consultancy | 0 |
| 4 | M Trummel & Associates Fire Protection | Consultancy | 2 |
| 5 | M-ma Partners Inc | Consultancy | 1 |
| 6 | M. Seligman & Co. Advocates & Notaries | Consultancy | 1 |
| 7 | M/s Rahman & Associates Ltd. | Consultancy | 1 |
| 8 | M+W Zander Holding AG | Consultancy | 1 |
| 9 | Maa Engineering Consultants Inc | Consultancy | 1 |
| 10 | Maa Engrg. Consultants | Consultancy | 0 |
| 11 | MacKay & Sposito Inc | Consultancy | 1 |
| 12 | Mackie Johnson Architect PA | Consultancy | 1 |
| 13 | Mactec Engineering & Consulting | Consultancy | 1 |
| 14 | MACTECH Engineering & Consulting Inc | Consultancy | 3 |
| 15 | Madeley Safety Engineering Consultants | Consultancy | 0 |
| 16 | Mahoning County Children Services Board | Consultancy | 1 |
| 17 | Mail & More | Consultancy | 0 |
| 18 | Maintenance Design Group | Consultancy | 1 |
| 19 | Majestic Urban Revivals | Consultancy | 1 |
| 20 | Malcolm Reading & Associates Ltd. | Consultancy | 1 |