QPR FC (@QPR) July 1, 2018
The German centre-back is QPR's first signing of the McClaren era and the former Derby County manager will likely base the rest of his defence around Leistner, who arrives with a glowing reputation.
The 27-year-old had gathered interest from Bundesliga and Championship clubs but, after speaking with McClaren, and getting some inside knowledge from former QPR striker and fellow countryman Sebastian Polter, west London was Leistner's only destination.
After speaking to QPR's official website, Leistner explained: "He [Polter] told me only good things about QPR. He said the fans were 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. QPR is a big club and a traditional club so it’s good to be here.
“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.”
Leistner will fill the void left by the Nedum Onouha, James Perch and Jack Robinson in the heart of the R's defence and could also be considered to skipper the side into the new season if he settles quickly.
Leistner made 29 appearances for Union Berlin in 2.Bundesliga last season scoring once and big things are expected of him during his time at Loftus Road.