The couple's first child was born June 15.
"Kim sort of explained it to me," Jenner told "Huffington Post Live" Monday about her granddaughter's name. "She said North is the highest power. And their baby North, their little girl, is the highest point and power between the two of them. So, I thought that was really cool."
Asked whose idea the name was, Jenner replied, "I think it was a joint decision."
"That's what I think. They did it together. Yeah, for sure," she said, adding she had no input in the naming decision.
"I stayed out of that one," Jenner said. "I did the same thing with [my daughter] Kourtney when she named Mason and Penelope."
Jenner's new talk show, "Kris," is to premiere July 15.