The Empire Strikes Back and Return of the Jedi writer will pen the script for a stand-alone movie separate from JJ Abrams's Episode 7 and future instalments 8 and 9.
Disney recently confirmed the plans, revealing that X-Men: Days of Future Past scribe Simon Kinberg will also work on an individual film.
Kasdan told the LA Times: "I'm trying to start fresh. There are certain pleasures that we think the saga can bring to people that they've been missing, and we're hoping to bring them that, and at the same time, have them feel that it's all new.
"The ones I worked on were a long time ago, and they had a slightly different feeling than the ones that followed. The first three, Star Wars, Empire and Return of the Jedi, are all sort of more about people than the ones that followed.
"George sort of brought me into this part of it, and he's stepping back from the company. He's sort of given his blessing to everybody, and he'll be there if you need him.
"I think everyone's interested to see where this can go. It's been some very different places over 30 years. I think with JJ, we'll get something entirely new."
Kasdan refused to confirm reports that the spinoff films would centre on iconic characters Han Solo, Boba Fett or Yoda.