| 1. Round | 17/03/2018 | Seattle Sounders 2 | - | Portland Timbers 2 | 2:1 | ||||
| 2. Round | 08/04/2018 | Sacramento Republic | - | Seattle Sounders 2 | 1:0 | ||||
| 2. Round | 15/04/2018 | Seattle Sounders 2 | - | Rio Grande Valley FC | 3:2 |  |
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| 2. Round | 22/04/2018 | Colorado Springs Switchbacks | - | Seattle Sounders 2 | 0:0 | ||||
| 3. Round | 06/05/2018 | Seattle Sounders 2 | - | Sacramento Republic | 1:2 | ||||
| 5. Round | 02/07/2018 | Los Angeles Galaxy II | - | Seattle Sounders 2 | 5:3 | ||||
| 5. Round | 08/07/2018 | Seattle Sounders 2 | - | Reno 1868 FC | 1:2 | ||||
| 5. Round | 27/07/2018 | Seattle Sounders 2 | - | Las Vegas Lights FC | 3:0 | ||||
| 6. Round | 05/08/2018 | Saint Louis FC | - | Seattle Sounders 2 | 2:0 | ||||
| 6. Round | 12/08/2018 | Seattle Sounders 2 | - | San Antonio FC | 3:2 | ||||
| 7. Round | 23/09/2018 | Rio Grande Valley FC | - | Seattle Sounders 2 | 3:0 |
USA