QPR’s promotion hopes took another blow as they produced another poor performance.
Goals from Mason Bennett and Tyler Burey made it back-to-back defeats for Rangers, who lost to bottom side Barnsley on Saturday and were well beaten at The Den, where Lee Wallace went off injured midway through the first half.
Millwall’s Danny McNamara missed a sitter in the opening minute when he blasted over from close range.
But there was no let-off for the visitors early in the second half.
Jed Wallace hit a diagonal ball and Albert Adomah switching off enabled Scott Malone to teed up Bennett, who slotted past keeper David Marshall.
Wallace was involved in creating the second goal as well, cleverly flicking the ball to Burey, who cut in from the left and found the far corner of the net.
Rangers have now failed to score in three of their past four matches and four of the past six.
QPR: Marshall; Dickie, Dunne, Barbet; Adomah (Austin 75), Field, Johansen (Amos 75), Wallace (Odubajo 21); Chair, Willock; Dykes.
Subs not used: Dieng, Hendrick, Sanderson, Gray.