Toni Leistner says he sought the opinion of Sebastian Polter before signing for QPR.
The pair were team-mates at Union Berlin, where German defender Leistner, 27, saw out his contract before deciding to join the R’s on a free transfer.
Polter, who joined QPR from Union Berlin in 2015 and returned to them last year, helped convince Leistner to move to Loftus Road.
Speaking to Rangers’ website, the centre-back explained: “He told me only good things about QPR. He said the fans are very crazy, positive and he loved playing here.
“I also met the manager and he convinced me with the style he wants to play. It made my choice easy.”
Leistner is Rangers’ first major signing since Steve McClaren took over as manager from the sacked Ian Holloway.
He has signed a three-year contract, having previously been linked with Norwich City and Aston Villa.
“QPR is a big club and a traditional club so it is good to be here,” he said.
“I like to play football the hard way. I love the physical side of the game and I hope I can give the supporters a lot.”
QPR have also signed Joe Felix, 18, after the right-back was released by Fulham.
Felix impressed during a trial last season and has been signed on a one-year deal following the end of his Fulham contract. He will initially play for Rangers’ development side.