"She is a good person, a strong individual. She'll fight this and come out a winner, as a more positive person. That's the way her career has been and that's why in her personal life too, she'll be a winner," Kareena said in an interview.
"As a family we are together and this is the time a family should stand together," she added.
Over the media attention that her sister's broken marriage was getting, Kareena said this was "part and parcel" of being a star.
"Stars and artistes should not look at it as being a disadvantage. They should look at it this way, if you are popular, people will come behind you.
If you are a public figure, people will talk about it," she said.
Karisma and her estranged industrialist husband Sunjay Kapur are embroiled in a legal battle over custody of their five-month-old daughter Samaira.