“Minister Wang Yi left Beijing earlier this morning for Geneva to join the Iran nuclear talks,” the foreign ministry said on its website.
“The nuclear discussions are entering their final phase,” it added.
Kerry earlier made a last-minute decision to fly to the Swiss city to help bridge gaps in the talks which have been going on since Wednesday.
French and German foreign ministers Laurent Fabius and Guido Westerwelle, as well as top British diplomat William Hague have also announced their arrival. Russian Foreign Minister Sergei Lavrov has been there since Friday.
Diplomats from the P5+1 group (which comprises the United States, Britain, France, Russia, China and Germany) and Iran have been trying once more this week to come to an interim accord on Tehran’s atomic programme, after a decade of failed efforts.
This third round of talks since President Hassan Rouhani’s election in June is seen as the biggest hope in years to resolve the standoff over Iran’s nuclear programme, which world powers want halted but which Tehran insists is peaceful.
Failure might mean Iran resuming the expansion of its atomic activities, Washington and others adding to already painful sanctions, and possible Israeli and even US military action.
Both sides say they want a deal but getting an accord palatable to hardliners in the United States and in the Islamic republic — as well as Israel — is tough.
According to a draft proposal, the United States, Britain, China, France, Russia, and Germany want Iran to freeze for six months key parts of its nuclear programme.
In return Iran would get minor and, Western officials insist, “reversible” sanctions relief, including unlocking several billion dollars in oil revenues and easing trade restrictions on precious metals and aircraft parts.