| # | Company name | Role | # of projects |
|---|---|---|---|
| 1 | X architekten | Architect | 1 |
| 2 | X-TU Architects | Architect | 4 |
| 3 | X’Téo Architectes SCM | Architect | 1 |
| 4 | Xanadu Architectes & Urbanistes | Architect | 1 |
| 5 | Xaveer De Geyter Architecten | Architect | 11 |
| 6 | Xavier Busquets i Sindreu | Architect | 3 |
| 7 | Xavier Donck & Partners | Architect | 2 |
| 8 | Xavier et Luc Arsène-Henry | Architect | 16 |
| 9 | Xerxes Architects Inc. | Architect | 0 |
| 10 | Xiamen Architectural Design Institute | Architect | 1 |
| 11 | Xosé Bar Bóo | Architect | 1 |
| 12 | Xquadra | Architect | 1 |
| 13 | Xsquared Architects | Architect | 3 |
| 14 | XTEN Architecture | Architect | 2 |
| 15 | Xuereb Martin & Associates | Architect | 2 |
| 16 | XVW Architectuur | Architect | 0 |
| 17 | XX architecten | Architect | 3 |