World number two Djokovic dug deep in the first set after an early trade of breaks to win a close tie-breaker and then broke the third-seeded Tsonga twice in the second set.
“I think the first set was really even and maybe a couple of points decided the winner there,” Djokovic told reporters.
“We both had our chances aside from those breaks that we converted… I managed to hold my nerve in the end.
“I made that early break in the second (and) I felt much more comfortable on the court.”
Sunday’s victory gave Djokovic, who also won the China Open in 2009 and 2010, his fourth title of the year.
“That’s the target,” Djokovic said. “This will definitely help me in that race but it’s still quite open. There are still tournaments to come, big ones.”
Tsonga said he needed to raise his game to beat top players such as Djokovic after his sixth straight loss to the Serbian.
“I think it was a good match,” Tsonga said. “I missed maybe something in the middle of the first set. I was a break up and I was playing well but then he played solid. It was really difficult to control him.
“I just tried to play my game, to be aggressive, but against a player like this, for the moment, my level is not high enough and it’s not enough to beat him.”
Earlier, Mike Bryan overtook Australian Todd Woodbridge’s mark of 83 career doubles titles when he, along with brother Bob, beat Carlos Berlocq and Denis Istomin 6-3 6-2 for their third China Open title in four years.
It was the seventh title of the year for the American pair.
(Writing by Sudipto Ganguly in Mumbai; Editing by Clare Fallon)
Nishikori rips Raonic to win Japan Open
It was the eighth seed’s second career title after winning in Delray Beach in 2008 and will elevate the 22-year-old from 17th to 15th in the world rankings.
“I’m partying tonight,” Nishikori said in a courtside interview as a sellout Tokyo crowd went wild. “I’d thought the Gods were against me at this event in the past.
“To win the title is amazing. I’m overwhelmed.
“I don’t know what I’m going to do with a year’s worth of Corona beer,” added Nishikori, sheepishly referring to a bonus gift from tournament sponsors. “I don’t even like beer.”
Nishikori took the first set tiebreak 7-5 after a jaw-dropping running backhand pass, clenching his fist to salute the roars of the crowd.
Sixth seed Raonic took the second, drilling a bullet serve at Nishikori’s body as the cheers of the majority among the 13,000 centre court fans turned to groans.
However, Nishikori stormed back in the decider, ripping another fierce backhand pass down the line to open a 4-0 lead, leaving his Canadian opponent gaping in disbelief.
He delivered the coup de grace moments later, a lofted return forcing Raonic to smash a drive volley into the net after two hours, eight minutes to complete a final set ‘bagel’.
Both players were presented with flowers by Australian Ken Rosewall, who won the title in 1973, the first year the Japan Open became an official tournament.
“Kei is a superstar in Japan,” said Raonic, who shocked last year’s winner and U.S. champion Andy Murray in the semi-finals and fired down 14 aces against Nishikori.
“Thank you Japan for your support,” added Raonic, who is projected to rise one spot to 14th in the rankings. “And thank you for inventing sushi. I love it.”
(Editing by Peter Rutherford)