The 63-year-old BVB chief believes the Germany international will remain at Signal Iduna Park for the foreseeable future, rather than leaving the club like Mario Gotze
The 24-year-old is the only BVB player with an exit clause in his contract, but Watzke believes the Germany international will not follow in the footsteps of Mario Gotze and move to Bayern Munich or any other club.
"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 £14.2m in January 2012, having being released from the club as a youngster, and has gone on to become a key player for both club and country, scoring 25 goals in 57 appearances for Jurgen Klopp's side.