Zesh Rehman's 80th minute own goal was enough to settle an ill-tempered affair after Rangers midfielder Stefan Bailey had been sent off for a vicious challenge on Ahmet Brkovic.
The result means Town will host Rovers in a televised affair on Saturday at 12.30pm.
The Hatters came into the game having had a bid for an unnamed striker verbally accepted earlier in the day.
On the field though, Town were forced to make five changes to the side that lost so dismally to Barnsley at the weekend.
With goalkeeper Dean Kiely having ended his second month's loan spell on Saturday, Marlon Beresford was expected to return between the sticks.
But the 37-year-old suffered a recurrence of an old back problem before the game, so Dean Brill came in for just his second start of the season, co-incidentally against the same opponents.
Elsewhere Kevin Foley, Adam Boyd, Russell Perrett and Brkovic came in for Keith Keane, Warren Feeney, Leon Barnett and Dean Morgan.
In front of another sparse crowd, both sides started tentatively as passes were sent wildly astray on the bobbly playing surface.
The standard of the early play was summed up by the nature of the first shot on goal when David Bell, playing in an unfamiliar striking role, cut inside from the right in the 13th minute and sliced a 20-yard left-foot effort that screwed away for a throw-in.
Some bizarre decisions from referee Michael Jones seemed to be the only thing keeping the spectators awake, until Rangers mustered a weak effort when Marc Nygaard looped a header harmlessly over from a Lee Cook free-kick in the 23rd minute.
Finally the game came to life with a chance for each team in the space of a minute midway through the half.
Firstly Bell streaked into the right-hand corner of the penalty area after latching on to Steve Robinson's 26th minute pass, only to drag his right-foot shot wide from 16 yards.
Seconds later Dexter Blackstock beat Perrett in Town's right-back position and whipped in a dangerous cross-shot that just eluded Nygaard, running in at the far post.
Brill, who had been recalled from his loan spell at Gillingham in order to play in the game, had looked nervous with a couple of kicked clearances.
However, he did his confidence a power of good with a fine double save just after the half-hour mark.
The 21-year-old dived low to his right to parry Chelsea loan man Jimmy Smith's 20-yard drive after Nygaard's lay off, and then recovered to block Blackstock's follow-up from point-blank range when the striker seemed set to open the scoring.
Luton rallied as Bell latched on to Sol Davis' slipped 37th minute pass and beat Simon Royce at his near post, only to see the effort disallowed for offside.
It was QPR that should have been ahead at the break though when Mauro Milanese marauded down the left seven minutes before the interval and crossed for Nygaard to somehow put a free header wide from four yards.
Nygaard was back in the action early in the second half when his right-wing cross flew behind off the crossbar three minutes in.
Both sides then created half-chances before QPR almost scored a sixth set-piece goal of the season against Luton just after the hour when Damion Stewart's thundering 12-yard header from Smith's corner flew just past the post.
Cook was causing the Hatters more and more problems down the left and a teasing run and pass set up Nygaard for another decent chance in the 67th minute, only for the lanky striker to hit his left-foot effort into the side-netting from eight yards.
The match then erupted in the 74th minute when Luton-born Hoops midfielder Bailey was sent off for a two-footed challenge on Brkovic that sparked a 20-man confrontation ending with Coyne being booked and Brkovic being stretchered from the field.
Morgan came on as a replacement and,11 minutes from time, he had a hand in the winner as his instant volley from the edge of the area flew in off Rehman for an own goal.
Morgan could have wrapped things up with two late chances, but Luton settled for the one-goal win.