The striker incurred the problem in training and could now be out until February to further add to under-fire manager Mark Hughes' problems.
Zamora has scored four goals in 12 appearances for QPR this season, although his last came in the 2-1 defeat at Tottenham on 23 September.
The former Fulham and West Ham striker last played for the R's in their 1-0 defeat at Stoke on 10 November, where he came off the substitutes' bench 12 minutes from time.
Zamora's injury then forced him to miss Saturday's 3-1 defeat to fellow strugglers Southampton and he now joins strike partner Andrew Johnson on the sidelines after he damaged his anterior cruciate ligament in September.
Djibril Cisse remains QPR's only remaining fit striker, with Jay Bothroyd, Rob Hulse and DJ Campbell all out on loan, with Jamie Mackie currently operating out on the wing.