Submission Underground 28 took place Sunday, October 31, 2021 with 10 fights in Portland, Oregon.
| Actor | Role |
|---|---|
 Andy VarelaSelf | Self |
 Haisam RidaSelf | Self |
| AAaron TiegsSelf | Self |
 Guilherme VasconcelosSelf | Self |
 Cris LencioniSelf | Self |
 Kevin LeeSelf | Self |
 Juliana MillerSelf | Self |
 Tara LaRosaSelf | Self |
 Kyle ChambersSelf | Self |
| TTanner WeisgramSelf | Self |
 Matt FerraioloSelf | Self |
| MMikey GonzalezSelf | Self |
| PPhelan CarronSelf | Self |
| MMorgan MatuizekSelf | Self |
| CCharles GilpinSelf | Self |
| RRoman WheelerSelf | Self |
| RReed WallaceSelf | Self |
| IIan KingSelf | Self |
| JJames ZengSelf | Self |
| CCaleb SteckerSelf | Self |