Reports had suggested he was reluctant to make a switch to Wearside from Down Under but he has moved to quash any talk of that.
"When I got permission to speak to Roy, once I spoke to him on the phone, that was it," he explained.
"He knew exactly what I thought. There is no doubt I wanted to be at this club.
"This club is massive in terms of a football perspective. There is no comparison between Sunderland and Sydney FC.
"Roy Keane as the manager played a major role in bringing me back here and, from a footballing perspective, this is the best thing that could happen to me.
"There are not too many people like Roy Keane around who have achieved what he has achieved in the game, so I am very happy and delighted that he wants me to come and play a major role at Sunderland."
Yorke also revealed he was not expecting to be an instant selection for the first-team because of his friendship with Keane."I am hoping it is not the case that the reason I am here is because I am his friend," said Yorke.
"I would like to think, from a football perspective, he sees me as a good footballer and I can bring something to Sunderland in terms of trying to get promotion.
"If I thought for a moment I was just his mate and I am going to get in the team because of that, I would not be here. I am not like that."
Yorke is expected to make his debut in tomorrow's game with Leicester City. Get yourselves there and make it a full house!