The 63-year-old believes the forward will remain at Signal Iduna Park and not follow Mario Gotze in leaving the club.
The 24-year-old is the only BVB player with an exit clause in his contract, but Watzke believes his player won't follow in the footsteps of Mario Gotze and move to Bayern Munich or any other club for that matter.
"Marco [Reus] feels very comfortable at Dortmund and we feel comfortable with him," he told Sport Bild. "He has an even closer relationship with the club and the city than Mario Gotze did and I expect him to stay.
"Marco was born here, his family live here and his whole life has always been based here. He knows that BVB is the perfect place for him. I am sure of that."
Reus joined Dortmund for 17.1 million euros in January 2012, having being released from the club as a youngster.
He has gone on to become a key player for both club and country, and has scored 25 goals in 57 appearances for Jurgen Klopp's side.
He has represented Germany 17 times, scoring on seven occasions.