The introduction is shown in the first episode of Caitlyn's new docuseries I Am Cait, which will detail her transition and life as a woman.
And although the cameras were there to capture it, the big moment wasn't planned to happen like it did. Kylie surprised Caitlyn when she FaceTimed her from the dentist, admitting she was "kind of loopy."
"I don't want to scare you," Caitlyn said, concerned about revealing her true self to the 17-year-old via a phone.
She needn't have worried, however, as Kylie gave a heartwarming reply saying: "You're not scaring me, you look pretty!"
The relationship between the pair seems stronger than ever, with Kylie calling Caitlyn "My angel on earth!" after her Vanity Fair reveal.
Caitlyn was supported by nine of her children last week, when she picked up the ESPY Arthur Ashe Courage Award.
I Am Cait begins Sunday 2, August at 9pm on E!
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