The 33 year-old Germany international joins BVB on a two-year contract.
"I am happy to be a Borussia Dortmund player," said Gross. "Signing for this club is a great moment for me, because I have been a Dortmund fan since I was a child.
"I will try to repay the club's trust in me by playing at my best and I can't wait to play together with my new teammates in front of the BVB fans at Signal Iduna Park and to work hard with everyone here to achieve our ambitious goals."
BVB chief Sebastian Kehl also stated: "We are delighted to bring Pascal back to the Bundesliga. His composure on the ball, his exceptional passes and his positional play and his versatility will add a new dimension to our team.
"But Pascal also has a keen eye for goal, representing a direct and indirect threat in many areas. We have no doubt that he will improve our way of playing and that he will be a real asset for us with his desire to win and his personality."