The Danish world number two was impressive all week in Beijing, never dropping a set and rarely looking troubled, sealing her spot in the WTA Finals Singapore in the process.
The 28-year-old Wozniacki, who won her maiden Grand Slam at the Australian Open at the start of this year, was imperious against the unseeded Sevastova, winning 6-3, 6-3.
It is her second China Open crown -- she also won it in 2010 -- and 30th overall.
"I'm just happy to have reached 30 today, I'm going to enjoy that," said Wozniacki, a former number one.
"As a little kid I had a dream of becoming a professional tennis player, becoming number one in the world.
"Then after number one in the world, I wanted to win a Slam, then I wanted to lift trophies.
"Having done everything, all of that, it's pretty amazing.
"I think I had a dream of that, but I don't know how realistic I really believed that was going to be."
Wozniacki, whose form has been patchy in the second half of the year, was ruthless on her serve and wrapped up the first set with an overhead smash to underline her superiority.
Sevastova, 28, will find herself just outside the top 10 in the rankings after her run in the Chinese capital.
"She didn't give me any presents, it was tough," said Sevastova, who retired in May 2013 because of persistent injuries, only to return in January 2015.
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