The Ghana captain had been playing his trade in United Arab Emirates since 2011, having initially arrived on a loan deal from Sunderland, and still had three years left on his contract with his Abu Dhabi-based employers.
However, Gyan will be formally presented as a Shanghai SIPG player next week after penning a lucrative two-year contract with the Chinese Super League side.
"I thank God for this special day, to my family, former team-mates at Al Ain and to my fans," the striker wrote on his official website.
"I reserve the rest of my comments for the official unveiling next week."
Shanghai SIPG, who are coached by Sven Goran Eriksson, have reportedly agreed to pay Gyan €315,000 per week, which would make him one of the top 10 highest-paid players in the world.
The 29-year-old attacker, who has netted 48 times in 90 appearances for his country, counts Rennes and Udinese among his former clubs.