Clark Engineers has worked with local, national and international clients. Below is a partial list of some of these clients.
| Baker Hughes CU | Mantex |
| Bay Products | Merichem |
| Biorem | Motiva Shell |
| Commercial Air | O’Brien & Geere Engineers |
| Construction Services | Owens Corning |
| Containment Solutions Inc. | Plascore |
| Continental Leisure Design | Poligon Systems |
| C & C Metals | Pro Plus Inc. |
| Dairy Queen (RCDQ) | Shell Oil |
| Enduro Composite Systems | Siemens |
| Epcom, Inc. | Stewart & Stevenson |
| Excel Tec | Tenaris |
| ExxonMobil | Tetra Technologies |
| Fina | Tisdale |
| FRP Manufacturing | Unistrut, Teconic |
| FRP Tank and Pipe Institute | Vogt Engineering |
| Hoffland Environment | West Wind Composites |
| Houston Industrial Fabricators | Woodlands Parks & Recreation |
| INSTAR | Xerxes |