The two clubs have come to an amicable agreement over a compensation figure for the winger following two months of negotiations, which will avoid the case going to a tribunal.
The west London club will pay Rovers €3.8m rising to €5m for Hoilett, who signed for Mark Hughes' team in July after his Ewood Park contract expired.
Although the 22-year-old had become a free agent, Uefa rules state that Blackburn are entitled to a training fee because the player is under the age of 24.
|15/2||Junior Hoilett is 15/2 with Paddy Power to open the scoring against West Ham on Monday night
Hoilett joined the Blackburn academy as a 13-year-old and went on to make 92 appearances for the first team before he moved to Loftus Road on July 27 after signing a four-year contract.
Blackburn were hopeful that a tribunal would award them a similar fee for Hoilett to the €7.5m paid by Chelsea to Manchester City when they signed Daniel Sturridge in 2009 but a maximum €5m is enough to convince the Championship club to stay out of court.
Hoilett was one of 11 new players signed by QPR during the summer in what was a radical overhaul of a squad that only avoided relegation from the Premier League on the final day of last season.
The Canadian claimed he shunned interest from Liverpool, Newcastle United and Sunderland to join the west Londoners.