After Sunday's 6-0 win against the Philadelphia Eagles, Witten ended any doubt.
"Oh, I'm back," Witten said. "I'm coming back. I love playing this game too much and I know that I can play it at a high level."
By returning in 2018, Witten will have more service time with the Cowboys than any player in team history. Ed "Too Tall" Jones, Bill Bates and Mark Tuinei each played 15 seasons with the Cowboys. Witten is already the team leader in most games played (239), most consecutive games played (235), most games started (229) and most consecutive games started (179).
He finished the season with 63 catches for 560 yards and five touchdowns. It is the 14th straight season he has had at least 60 catches. Only Jerry Rice (17) and Tony Gonzalez (15) had more consecutive 60-catch seasons than Witten.
Witten, who is 35, signed a four-year extension with the Cowboys last March, but he has contemplated retirement the past two years.
"I know this: The burn is strong inside me to play at a high level and to be a part of one of these groups of guys and one of the leaders to see this thing through and go try to compete for a championship," Witten said. "When I wake up tomorrow, that's where my focus will be on as I move forward. It hurts because you don't get a whole lot more opportunities at this and I realize that, but rest assured that I'm going to do everything in my power to help us be better as we move forward. And I think it needs to be clear that it starts with yourself."