Morrison will officially complete the move on Friday and will stay with the Sky Bet Championship promotion chasers until after the play-offs in May.
The England Under-21 international got off to a fine start to the season but has since struggled for playing time, making just one Premier League appearance off the bench since Christmas.
But he is excited about the chance of taking the R's into the top division and he could make his debut in Saturday's clash away to Charlton.
QPR are currently in fourth place, four points behind second-placed Burnley but with a game in hand on them and Derby who sit in third.
Morrison told QPR's official website: "I just want to help QPR get to the Premier League - that's my only objective during my time here.
"If we manage to do that, it would be great for everybody connected with the club. All I want to do is play football. I just want to show everyone what I can do week in, week out.
"The aim here is to get the club promoted and I want to contribute in helping QPR to get there."
QPR manager Harry Redknapp is hoping that Morrison can help the Hoops in their promotion bid.
"Ravel is fit and ready to play and I'm hoping he can come in and make an impact," said Redknapp.
"He's got fantastic ability, there's no doubting that. He's got great pace, can dribble and score a goal.
"If we can get the best out of him, he could make a big difference.
"He's certainly a talented footballer - he's just got to step up now. He's got to come here and show what he can do consistently. He's got everything.
"We're pleased to have him here."