The result at the Maria Lenk Aquatics Center continued China's remarkable sequence of results in the event. China has won every world and Olympic title in the women's synchronized springboard since the 2000 Sydney Games.
The performance also secured a raft of records for veteran Wu.
The 30-year-old has now won the most Olympic diving medals by a woman, surpassing compatriot Guo JingJing with seven podium finishes.
She also became the oldest woman to win an Olympic diving medal, overtaking the USA's Micki King, who was 28 when she won the springboard title in 1972.
In addition, Wu equalled the record held by Canada's Emilie Heymans for diving medals in the most Olympic Games (four).
Earlier in the Carioca Arena 2, Majlinda Kelmendi made history by winning Kosovo's first Olympic Games gold medal in judo's women's 52kg final.
Kosovo is represented at an Olympic Games for the first time in Rio and Kelmendi gave Kosovo a moment to treasure by seeing off Odette Giuffrida of Italy in the final, scoring a yuko for her victory.
Kosovo makes its debut at the Rio Olympic Games, having been officially recognised by the International Olympic Committee in December 2014. Kosovo therefore became the 100th delegation to win an Olympic gold medal.
"I'm so happy for me, for my coach, for all my country. This is the first time that Kosovo is part of the Olympics, and for the first time, I think the gold is huge," said Kelmendi.
"That means a lot. People, especially kids, in Kosovo look to me as a hero. I just proved to them that even after the war, if they want to be Olympic champions, they can be. Even if we come from a small country, poor country."
History was also made by South Korean women's archers, who maintained their unbeaten record in the Olympic team event by beating reigning world champions Russia 5-1 to take the gold medal.
Since the team events were first added to Olympic Games in 1988, South Korea have swept all the eight women's team golds.
The Olympic Aquatics Stadium witnessed three new swimming world records, with Katie Ledecky of the United States winning the women's 400m freestyle in 3 minutes 56.46 seconds, Britain's Adam Peaty shattering his own world record for the men's 100m breaststroke in 57.13 seconds and Sweden's Sarah Sjostrom claiming women's 100m butterfly with 55.48 seconds.
Michael Phelps-led USA also won the men's 4x100m freestyle relay gold, and it's Phelps' 19th Olympic gold medal.
Elsewhere in tennis competition, world number one Novak Djokovic was shocked in the first round by Argentina's Juan Martin del Potro, a shock result that reduced the Serb to tears as he left the court.
Djokovic can complete the Golden Slam by adding a maiden gold medal in Rio, but now he has to wait four more years for the golden sweep. There's also stunning loss for three-time doubles gold medalists Serena and Venus Williams, who lost in the first round.
The USA now tops the medals table on three gold, five silver and four bronze medals, with China trailing behind with three gold, two silver and three bronze medals.
