In a video clip that preceded Caitlyn's acceptance speech at the magazine's 25th annual Women of the Year awards, Kylie opened up about how the star's transition hasn't changed their close relationship.
"I was a little scared because I didn't know how much would change," Kylie, 18, admitted.
"And it honestly feels like, besides appearance, nothing has changed."
Caitlyn, 66, was recognized for her advocacy work in the LGBT community.
The Olympian announced her transition in an April interview with Diane Sawyer before introducing herself as Caitlyn on Vanity Fair's June cover.
"She's lived an amazing life, and she's always done amazing things," Kylie continued in the clip.
"She's such a good role model for so many people, and I know she wants to do so much good with what she's doing."