Kardashian told reporters in New York at Friday's Variety Power of Women event — where she was being honoured along with Lena Dunham, Whoopi Goldberg, Glenn Close and Rachel Weisz — that people assume there's a divide in her family, which isn't true.
"We always support each other. Our family is super supportive of everything that we do and you know we're gonna watch the special tonight and support Bruce and watch it with him tonight."
Jenner's two-hour interview with Diane Sawyer is set to air on ABC at 9 p.m. EDT Friday.
Kardashian said she planned to catch a flight back to LA immediately following the luncheon.
Jenner and Kim's mother, Kris, divorced in December of last year after 25 years.
ABC hasn't confirmed exactly what the 1976 Olympic decathlon winner will say in the interview with Diane Sawyer, but has promoted as "wide-ranging."
It's expected he will talk about transgenderism amid reports that he may be transitioning to a woman.