The HBO series stars Melissa Leo, John Goodman and Steve Zahn as New Orleans natives dealing with the aftermath of Hurricane Katrina.
Deadline reports that at a recent screening of the show's season three premiere, Simon announced his plans to end it next year.
He said: "We are going to be back for a season 3.5. HBO, upon viewing the ten [episodes from Season 3] that we gave them and what we've done, they want to see the end of the story. They fought very hard to give us half a loaf. We're going to take it and run."
Season 4 of Treme will reportedly be cut in half at the request of HBO bosses.
The third season premieres today (September 23) on HBO.
Watch the Season 3 trailer for Treme below: