The singer, actress and designer will mentor alongside Nicole Richie and John Varvatos in the Elle MacPherson-produced competition, which will see designers competing to win the multi-million prize of launching their collection at one of America's top retailers.
In an NBC video, she said: "I take mentoring very seriously. Even when I was a young girl I felt called in my life to be a leader. I always felt I have a voice and it should be heard.
"I know I have a sensitive spot and an endearing spot and a challenging spot to make someone go to the next level. I have to push myself daily so it's nice to be able to have other people to push along with me, so as a mentor I'm always inspired and it makes be a better person."
Watch Jessica Simpson talking about Fashion Star below:
In the video, the star also revealed her hopes for her own billion dollar design brand, saying she wants to follow in the footsteps of designers like Ralph Lauren and launch a homeware collection.
"I like all different kinds of designers," she said. "I love to mix all different kinds of designers, but I think it's important to have that all-American brand, at least it is for me.
"I look to a Ralph Lauren or a Michael Kors, somebody who can do it all. Ralph Lauren definitely does it all. Eventually one day you will be sitting on a Jessica Simpson couch, I guarantee it!
"There are no limits to where I want to go and I want these designers to feel that as well."
Fashion Star's format will see buyers from Macy's, Saks Fifth Avenue and H&M deciding whether they want to purchase and exclusively carry the work of the designers following each week's challenge.
Any designers who do not sell any items to the buyers will be up for elimination, although Simpson, Richie and Varvatos will be able to save one of them from being sent home.
All designs will be available for viewers to purchase immediately after the show.
Fashion Star launches Tuesday, March 13 at 9.30/8.30c on NBC
> Jessica Simpson: 'Being Fashion Star mentor is dream come true'
> Jessica Simpson: Fashion Star is great shopping show for the ladies