Phil Jagielka grabbed two with Chris Morgan and substitute Vincent Pericard weighing in with one each.
It was more than enough to dent the ambitions of Luton, last year's League One top dogs and this year's surprise package.
And the comfortable victory put Untied back on track after they dropped their first home points of the season with Saturday's goalless draw with Cardiff.
Mike Newell's men had flashed an early warning in the first minute when Carlos Edwards burst forward and lashed in a long-range shot, forcing a save from Paddy Kenny.
But after that it was United's night as they took control with an impressive swaggering display.
United winger Alan Quinn tormented the Town defence and frustrated Kevin Foley lashed out with a rash challenge that earned him a booking.
And Quinn was the creator when United made the crucial breakthrough after 34 minutes, when midfielder Jagielka claimed his third goal of the season.
Quinn's tricky free-kick had Luton keeper Marlon Beresford stretching to punch out as far as Paul Ifill, who smashed a volley into a crowd of players. Morgan's scuffed shot trickled to Jagielka who stabbed in from six yards.
Five minutes into the second half Morgan put United in the comfort zone with his first goal of the season.
Danger man Quinn swung in another testing free-kick and as keeper Beresford was caught off his line Morgan placed a clever header wide of him to stretch the lead.
And substitute Pericard killed off the Hatters in the 70th minute when he slid in to force his low shot in after Derek Geary's cross from the right.
Jagielka sealed the rout with and emphatic strike from 15 yards after impressive work from substitute Danny Webber.