The 20-year-old, already a winner in the 10m synchronised platform in Rio, scored 585.30 points after his six dives -- breaking the 100-point mark for three of them.
Mexico's German Sanchez won silver (532.70) with American David Boudia, the gold medallist from London 2012, taking bronze (525.25).
Chen's teammate Qiu Bo, a silver medallist behind Boudia in 2012, dropped to sixth place after missing two of his dives.
The only title China failed to win in Rio was the men's synchronised 3m springboard where Britain's Jack Laugher and Chris Mears told gold.
Earlier Tom Daley's Olympic gold bid ended in heartbreak as the Briton finished a shocking last in the semi-finals behind Chen and Qiu.
The 22-year-old Daley looked set to improve on his London 2012 bronze after finishing first in Friday's preliminary round ahead of the Chinese pair.
But Daley endured a rocky first three rounds at the Maria Lenk Aquatics Centre and after failing to pull back in the remaining three he finished last of the 18 competitors, with the top 12 advancing to Saturday's final.