While he's away, Stewart says he'll miss hosting the Comedy Central fake newscast.
As he explains, "People clap for me! That doesn't happen just anywhere."
Stewart will be directing and producing "Rosewater" from his own script, based on a memoir by Maziar Bahari. This Iranian journalist was falsely accused of being a spy and imprisoned by the Iranian government in 2009 while covering Iran's presidential election.
Pressed for more details about the film, Stewart cracked, "I haven't seen it yet. But I hear it's good."
After Stewart signs off Thursday night until returning Sept. 3, correspondent John Oliver will handle anchor duties on the New York-based show.