Gundogan compared the winger's experiences to his own early career move.
"It is only normal that Leroy is still finding his feet at Manchester City," Gundogan told Kicker.
"I think Leroy has the character and personality to cope with this situation. He is confident and is well aware of his own qualities.
"You can see that he is still a bit shy, but he is still only 20. I went through a similar situation when I joined Dortmund from Nurnberg, so I know how he feels.
"He will do his own thing and he will do so here at Manchester City as well. I am giving him all the support he needs."