Kylie, 18, set up a profile on Bumble for Kourtney, who split from her longtime partner and father of her three children, Scott Disick, last year, reported Contactmusic.
Admitting she had taken 37-year-old Kourtney's phone, Kylie said on Snapchat, "I have Kourtney's phone, I know her password. Should I go through her text messages and read them to you guys?
"I think she's gonna kill me if I read her text messages, so I think I think I'm gonna set her up for Bumble. I think she needs to be on Bumble."
Kourtney, who has children Mason, six, Penelope, three and one-year-old Reign with Scott, has been single since their split, although she was linked to Justin Bieber, 22.