The pair led the event from the first round and finished on 490.35 points - becoming the second Chinese diving pair to top the podium so far at the Paris Olympics.
Tom Daley and Noah Williams of Britain took silver with 463.44 points, followed by Canada's Ryan Wiens and Nathan Zsombor-Murray who won bronze.
Yang and Lian have dominated the world championships in the last three years in the event but it was their first time to stand on top of the Olympic podium.
The Chinese pair, the 7th to start, kicked off their routines with a forward dive in pike position and immediately established their lead.
Their skill in their last dive and the most difficult routine in their programme – the forward four-and-a-half somersault with a near-perfect entry - landed the event’s highest score on Monday, 103.23 points.
"We've held our breaths until after the very last dive," Lian told reporters after the event. "There is after all so much uncertainty in the competition. We couldn't have been entirely relaxed until the end."
"When we first saw the draw that the British team would dive right before us, we felt some pressure as they were also an excellent pair, but we did better today and that was how we won," he said.
Daley fell short of upsetting China's dream team but he and his partner Williams received roaring cheers from the fans, as they witnessed what might have been the 30-year-old five-time Olympian's last Games performance. Daley has not said what he plans to do after Paris.
"The Chinese did absolutely incredible today. They were on incredible form. Every single one of their dives was flawless," said Daley of his Chinese opponents.
Daley and Williams started training as a pair only 9 months ago. Daley had stepped away from the sport after the Toyko Olympics in his long Olympic journey that first started as a 14-year-old in Beijing 2008.
"For me, the achievement was getting back to competition readiness within a year (which) is something I didn't expect to be able to do," he said.
Canada's Wiens and Zsombor-Murray walked away the pool with a big smile as they claimed their first medal in an Olympic diving event.
"It is absolutely amazing, unreal," Wiens said. "When we just got the results in and found we were third we were jumping up and down and the feeling was surreal."
Chen Yiwen and Chang Yani won China's first diving gold on Saturday in the women's synchronised 3-metre springboard event.
