Kylie Jenner models in Avril Lavigne's Fashion Week show

Singer and designer Avril Lavigne's two worlds combined Monday at the New York Fashion Week show for her punk-rock clothing line Abbey Dawn.

"Keeping Up with the Kardashians" star Kylie Jenner opened the show, strutting down the runway in a black and white babydoll dress to Lavigne's 2002 hit song "Sk8er Boi" as sister Kendall Jenner looked on, snapping photos and cheering in a floral crop top and jeans.

Skull prints stole the spotlight in the Spring 2013 collection, adding edge to tight dresses, cropped Tees, jeans and shorts as Lavigne's soundtrack continued.

"I design pieces I would love to wear on stage," Lavigne said. "It's all about rock and roll, being free and expressing yourself."

Jenner wore three outfits during the show, but she said her final look was her favorite: a pair of red shorts with a white tank and a black lace jacket with a leather studded collar.

"The jacket was so cool," she said.

Lavigne's relationship with Jenner's brother Brody has ended, but there seemed to be no love lost between the singer and her model.

"I love Avril," Jenner said. "I love her; I love her clothes, so it was such an honor to be in [her show]. It was so much fun."

Another ex of the family was also in the house, singer Adrienne Bailon, who dated Rob Kardashian.

Photo: Kylie Jenner poses with Avril Lavigne after modeling in her Abbey Dawn show at New York Fashion Week in Manhattan. (Sept. 10, 2012)