The star, 40, is the oldest of the Kardashian sisters and has been in the popular E! Network series since its inception in 2007.
Kourtney, who has three children with ex-partner, property business owner Scott Disick, has also starred in six of the television show’s spin-off series.
Speaking to Entertainment Tonight, she said: “I’ve just decided to spend more time as a mum and put more of my energy there. But I’m not saying goodbye. You’ll have to see more of it on the 18th season, which is being filmed currently.
Her sister Khloe said the show will be able to continue without her.
“We love Kourtney, and we will miss Kourtney, and whatever she decides to do,” she said. “But people come and people go all the time in this family, we feel like it’s a revolving door. So Kourtney might leave this week, she’ll come back. They all come back.”
Other guest stars include Disick, Kris’s partner Corey Gamble, Kanye West and the children of Kourtney, Khloe, Kim and Kylie.
In addition to starring on the show, Kourtney runs her own lifestyle brand, Poosh.
It is named after her daughter, Penelope, who is nicknamed Poosh by the family.