The 35 year-old Socceroos ace confirmed he has agreed terms on Tuesday morning in Sydney after discussions with David Moyes about a possible move to Real Sociedad and advice from the likes of Australia national team coach Ange Postecoglou and French ace Thierry Henry.
Cahill said that while he respects the league in Australia there was no offers from any A-League clubs and that he will continue to be available for the Socceroos.
"I've taken a lot of good advice from very powerful men. I think it's exciting. To be in demand and have these offers is special," Cahill said.
"You have to ask yourself what you want. I've never chased the money. If I did I would have been in Qatar or China before New York Red Bulls.
"I will make an impact in China, I promise you, on the pitch. When I go somewhere I'll do it properly.
"I think it's exciting. To still be in demand and have the offers I've had is special but this will be massive for me as a player on and off the park.
"I'm not only a footballer, I'm someone who's an ambassador for their country."
Major League Soccer side New York confirmed Cahill's exit by mutual agreement after three years in America's top flight.
"This decision was not made lightly, and it is the result of many conversations between our staff, Tim, and his agent," Red Bulls Sporting Director Ali Curtis said.
"After much deliberation, we have agreed that this decision is best for all involved. We thank Tim for his service to the organization. He positively impacted the growth of the beautiful game in the United States, MLS and for the Red Bulls.
"We are pleased that Tim will continue to be an ambassador for Red Bull moving forward."
Fresh from Asian Cup success with Australia, Cahill is now looking forward to the next phase of his career after being linked with moves to the UAE, Qatar and the English Premier League before selecting China as his next destination.
"I've done the Premier League, I've done America. New York was amazing for me but China is a growing market in football," Cahill said.
"You see in the Asian Cup quarter-final game that we played against China, millions of people watched it and I'm someone who is embracing culture and a different aspect of life.
"I'm at an age where I want to give something back to football and still play at a high level.
"To play in so many countries, I'm blessed. This will be massive for Tim Cahill.
"I joined with the ambition of helping to grow and positively affect soccer in the US and I feel immensely proud of what we achieved as a team during my time in the MLS," he told Red Bulls' official website.
"Winning the Supporters' Shield was, without doubt, one of the best moments I have experienced in my career and I am now looking forward to my next chapter, of which I will announce in due course."
