The 35-year-old Socceroos star, who scored three goals for Australia during a triumphant run to the Asian Cup title, said he was attracted by the scale of the potential football market in China.
"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 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."
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Cahill scored 14 goals in two-and-a-half seasons since joining the Red Bulls in July 2012.
Cahill, who scored twice for Australia in last year's World Cup in Brazil, helped the Red Bulls win the 2013 MLS regular season crown, the Supporters' Shield, when he was named in the league's Best 11 and All-Star teams.
"After much deliberation, we have agreed that this decision is best for all involved," Red Bulls sporting director Ali Curtis said.
"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.