Mikel had a medical in the port city some 130 kilometers from Beijing on Thursday and the Asian Football Confederation confirmed the deal on Friday.
Mikel's move comes on the day China's leading sport’s governing body announces plans to cap the spending of the country's super league clubs.
Nigeria international Mikel penned a letter to his "Chelsea family" and tweeted it to his followers on social media.
"To play in the Premier League, the best league in the world, is every professional player's ambition," said Mikel.
"But to play for Chelsea, to become part of the Chelsea family, to work with some of the best managers and players in the world, has truly been an honor...to everyone at Chelsea - goodbye, and thank you.”
"You will always be part of who I am."
A letter to my Chelsea family.
The 29-year-old, who spent more than a decade at Stamford Bridge, was given a free transfer by the London club and will earn £140,000 a week in China, according to local media reports.
"As you will know, I haven't featured as much this season as I would have liked, and at 29 I still have many years in the game ahead of me," he said.
"With this in mind, I feel now is the time to seek a new challenge.
"I'm delighted to be joining Tianjin TEDA FC in China, at a time that the Chinese Super League is really taking off, and I look forward to helping Tianjin TEDA FC continue to grow both on and off the pitch in the next few years."
Mikel won 11 trophies with Chelsea during a spell at the club which consisted of 374 appearances.