The 28-year-old joined Rovers on Monday morning and will be in contention to make his debut away to Wigan Warriors on Friday.
Trout made his Super League debut for Wakefield in 2012 and played 25 times for Trinity until 2015.
He dropped into the Championship for spells with Sheffield Eagles and Dewsbury, where he has been ever-present this year.
Rovers have paid Rams an undisclosed fee for Trout who said: “I’m really excited to get another crack at Super League. I’ve had a few years in the wilderness now so it’s great to be back.
“I’ve worked with [KR assistant coach] James Webster at Wakefield before and things didn’t work out for one reason or another, but now I’m here and I get another chance .
“I have the opportunity now and it’s up to me to take it. I want to prove some things to myself as well as everybody else, that I am good enough for this level."
Trout will be among familiar faces at Rovers.
He added: “I know Ben Crooks and I’ve played with Robbie Mulhern earlier in my career.
"I came through the amateur game with Danny Addy and Owen Harrison played on loan for Dewsbury for us earlier in the season. I’m looking forward to getting to work with my new team-mates now and I’m playing for a deal for next year.”