Clark said: “I feel this is a good opportunity for me at this moment in time. I have had a good pre-season with Castleford and I am pleased to be joining a top-four Championship club, one which is heading in the right direction.
“It will be a great opportunity for me to get some game-time, at a good level and I will be bringing plenty of energy to the team.”
Tigers coach Daryl Powell said: “Mitch is a player who is working hard within our system and improving all the time and it will be great to see him play in the tough competition the Championship is.”
Rovers head coach John Duffy said: “The opportunity to bring Mitch to Featherstone came up and it was something we could not afford to turn down.
“We believe he will come here and add a great deal of value to our squad, bringing further competition for places. His aggressive nature will suit our style of play.
“I am really looking forward to seeing him take to the field in a Featherstone shirt. I have always admired Mitch while coaching against him.”