The Queensland state of Origin star said: “This was without doubt the toughest decision of my career.
“But there are other areas of life I want to explore and living abroad and travelling is absolutely up there on the list.
“The opportunity to continue my rugby league career with the security of a long-term deal and in such a beautiful part of the world was one that I couldn’t refuse.
“I have always wanted to play in Super League and I could think of no better Club to do it at than Catalans. After winning the NRL and the State of Origin I want to win the Super League. They were not far from the Grand Final last year and I am certain with the quality of the players we have in this squad we can do even better.”
Dragons Head Coach Kevin Walters said: “I am delighted to secure the services of Dallas Johnson. He is a champion player who will bring a lot to our team especially thanks to his exceptional defensive skills. Dallas is a natural leader and is exactly the type of player the Dragons need to keep improving year after year. I am sure our supporters and sponsors will love Dallas attitude and commitment to the club both on and off the field.”
Storm CEO Brian Waldron said: “It’s with a heavy heart that we’ve agreed to the release request.
“This is a great opportunity for Dallas and his wife, Mel, and as a club we would never stand in the way of such a great life experience that awaits.”
Johnson is due to arrive in France in early December for pre-season training once he is granted a working visa.