The duo, who have been on-again, off-again for years already share three-year-old daughter, Stormi. But it seems that they aren't stopping at just one.
According to a TMZ source, Jenner is still in the "very early stages" of the pregnancy and is still in the dark about the sex of the baby. The outlet has still not been told when the new baby is due.
The exciting news comes in the midst of pregnancy rumors that have surrounded the billionaire in recent months.
It was later reported that Caitlyn's eldest son, Burt, is expecting his third child with wife Valerie.
But rumors of another pregnancy from Kylie weren't going to slow down. Just last week, fans noted that the Kylie Cosmetics founder was apparently missing from most of the snaps of her 24th birthday bash, and they quickly began wondering if the KUWTK alum was hiding something.
One user pointed out that Kim posted throwback photos for her little sister's birthday on Instagram instead of sharing photos from the party.
On Friday, Jenner posted an Instagram story featuring a boomerang video of herself in the mirror, but she didn't seem to be showing a baby bumb in the clip. However, fans have started to speculate that Jenner has been posting old videos and photos of herself to throw fans off track.
Fans might not be surprised by the pregnancy news considering that OK! already reported that the reconciled lovers were trying for another little tot.
"Kylie and Travis are doing great. They are in the best place they've been in years," a source reported earlier this summer, adding that they "have been trying for baby number two for the past two months."