The 14-year-old, who appeared in a string-bikini in a recent photo shoot, has sparked controversy due to her young age.
Jenner told Us Weekly: "Because she is 14, all of a sudden [people are like], is it right for a 14-year-old to do? She wasn't showing anything that was inappropriate - you know, too much cleavage or anything like that.
"They were just like hot shots. I saw the pictures and I said, 'OK.' If that is what she wants to do, she wants to be a model, then more power to her."
Kim Kardashian recently said that she was giving advice to her younger sisters on how to model.