The Forever Knights reappear in Ben 10: Alien Force. Here they are allied with the Highbreed and the DNAliens, although they are unaware of their true intentions. The Forever Knights now dress in full plate armor with an infinity symbol on the abdomen, as opposed to the more medieval-style armor they wore previously. They use Laser Lances as their main weapon while higher ranked Forever Knights use a sword to signal attacks. Their main base of operations is shown to be an old castle. The Forever Knights want to eliminate Ben, Gwen and Kevin Levin after they helped the alien dragon escape.
The Forever Knights (alien force) appear in Ben 10 Alien Force episodes Ben 10 Returns Part 1, Ben 10 Returns Part 2 and Be-Knighted. The Forever Knight's headquarters is the Forever Knight Castle.