Submission Underground 25 took place Sunday, July 18, 2021 with 9 fights in Portland, Oregon.
| Actor | Role |
|---|---|
 Pedro MarinhoSelf | Self |
 Andy VarelaSelf | Self |
 Edwin NajmiSelf | Self |
 Jeremy KennedySelf | Self |
 Keith KirkorianSelf | Self |
| JJoseph MckaySelf | Self |
| GGustavo PiresSelf | Self |
 Nick MaximovSelf | Self |
 Colton VaughnSelf | Self |
| EEric McConicoSelf | Self |
| AAaron TiegsSelf | Self |
| ZZachary MinteerSelf | Self |
| ZZack SchneiderSelf | Self |
| KKevin ShaughnessySelf | Self |
| IIghor HortaSelf | Self |
| JJames ZengSelf | Self |
| AAlex LarmeySelf | Self |
| JJosiah IwamizuSelf | Self |