West Ham have sold Jose Fonte to China's Dalian Yifang.
The fee involved is undisclosed.
The Portuguese joined the Hammers from Southampton in January 2017, moving in a £8million deal from the south coast club having won Euro 2016 the preceding summer.
“I think Jose wanted to take it," manager David Moyes told reporters earlier on Friday. "He's 34 years old, he felt that it was the right thing for his career at this time, gave him the chance to try something new.
"He wants to get in the Portuguese national team for the World Cup and felt if he was playing regularly it would give him a better chance.
“He's just back from injury and in a condition to play so we wish him good luck and he's been a great professional since I've been here."