(Cover) - EN Showbiz - Kim Kardashian has bemoaned the fact that her younger sister Kylie Jenner is "growing up way too fast."

The 31-year-old reality star took to her blog to wish her sibling a happy 15th birthday and to share her thoughts on the young model's path.

Kylie first appeared on Keeping Up With The Kardashians in 2007 and has grown up in front of the reality television cameras.

"[Kylie] is stunning, silly, smart, talented and funny," Kim wrote but added that she is "growing up way too fast for my liking."

"But what an amazing and beautiful young lady [she has] turned into. We are all so proud of [her] and I can't wait to see what the future has in store."

Fellow big sister Kourtney Kardashian, who welcomed her first daughter Penelope last month, also added her best wishes.

"You are filled with so much fun and happiness but so nurturing and understanding at the same time," the 33-year-old mother-of-two said.

"You have wisdom beyond your years and I'm proud to call you my sister." (C) Cover Media