Waititi told fans at Marvel's panel talk at Comic-Con San Diego this weekend that Natalie Portman is not only back for the fourth instalment, but that she'll play female Thor.
The Kiwi writer, actor and director reportedly said the film "introduces a female Thor for the first time," before bringing Portman out on stage, holding Mjolnir, Thor's hammer-like weapon.
The film will be titled Thor: Love and Thunder, and is scheduled for release in November 2021.
Love and Thunder will run in line with the Marvel comic series, which sees Portman's character Jane Foster take on the role of Thor.
Foster spent the first two films as Thor's love interest, but was notably absent from Thor: Ragnarok.
The Comic-Con announcement also makes the Thor franchise the first in the Marvel Cinematic Universe to break the trilogy model.