This week's WTA results in New Haven mean she is guaranteed to finish in the world's top eight, who will all compete at the prestigious event in Turkey.
The world number two is the second player to qualify for the tournament, after Serena Williams.
She has won the Australian Open this season, as well as titles in Doha and, just last weekend, Cincinnati.
"I'm super excited to have qualified," Azarenka said. "Making the Championships is one of my goals every year and it really shows your consistency through the season.
"We have so much fun in Istanbul; it's one of the best events and a beautiful facility. I'm looking forward to seeing all the fans, the excitement and energy they bring is just amazing."
WTA chairman and chief executive Stacey Allaster said: "Congratulations to Victoria on a great season thus far.
"Successfully defending a Grand Slam title is an incredible achievement, and her thrilling title runs, most recently at the Western and Southern Open, have showcased her fighting spirit and determination to win. It will be terrific to have her back at this year's TEB BNP Paribas WTA Championships."
It is the fifth season in a row that Azarenka has qualified for the event. Her best effort so far is a runners-up finish in 2011.
The tournament is being held from October 22-27. It is the last year it is being staged in Istanbul with next year's host city being Singapore.