Full-time from the KC StadiumA sizzling four-goal first-half blast by Hull City condemned The Lions to their second away defeat of the campaign.
Robert Koren (14mins), Jay Simpson (30mins), Abdoualaye Faye (36mins) and Sone Aluko (40mins) were on target as Steve Bruce's men ran riot against Millwall in a forgettable opening 45 minutes for the visitors.
But credit to Kenny Jackett's shell-shocked Lions, who dug deep and produced a second-half performance that went some way to restoring their battered pride with Darius Henderson's 63rd-minute header adding some respectability to the score-line and a reward for a much-improved display.
"Hull were very impressive today and I have no complaints, they worked the ball very well with their system to get themselves into shooting positions," said Jackett.
"We got ourselves in some very good positions in the second half, especially with James Henry going down the right hand side. I wasn't disappointed with the second half, but it had an unrealistic feel about it."
Millwall welcomed back Paul Robinson for the first time this season after the skipper had been sidelined following a double hernia operation.
Manager Jackett opted for a 3-5-3 formation with Robinson, Shane Lowry and Karleigh Osborne the trio, supported by Scott Malone and James Henry as wing backs.
But the stats don't lie, however, and Hull chalked up an incredible 26 shots on goal - 17 on target - as they gave The Lions rearguard their toughest afternoon of the season so far.
The first of these came with less than 55 seconds on the clock as The Tigers tore into the visitors from the off and Aluko's fierce drive tested Maik Taylor in the Millwall goal.
Taylor was called into action again on five minutes when, seconds after a deep James Henry free-kick had been cleared, former Lions loanee Simpson picked out Ahmed Elmohamady in space on the right, but his low drive was comfortably held by the keeper.
Millwall stopper Taylor came to the rescue just before the 10 minute mark when The Lions struggled to clear their lines and Robert Koren's shot took a wicked deflection; the ball spun up and over the keeper, who somehow plucked it out of the air to avert the danger.
The Lions responded and an unmarked Henderson wasted the best chance of the game from the first corner on 13 minutes, placing a header wide of the target from Henry's pinpoint delivery.
That proved to be a costly miss and within 30 seconds Hull had taken the lead as Koren had time and space to pick his spot from 25 yards.
Scott Malone saw his left foot effort hit Abdoualaye Faye and loop onto the roof of the net and then Henderson's angled effort was held by Ben Amos in the home goal as Millwall tried to conjure an instant response.
But it was Hull who struck again when Stephen Quinn's teasing ball from the right found Simpson who took one touch and hammered into the roof of the net from close range to make it 2-0.
Matters went from bad to worse when Hull added a third courtesy of Faye's textbook header from a Jack Chester delivery nine minutes before the break.
And in a blink of an eye it was 4-0 and effectively game over when the Millwall defence was breeched for a fourth time, on this occasion referee Alcock waving play on after a Robinson foul on Simpson allowing Aluko to drill a clinical low finish beyond Taylor's reach.
Hull could have been five goals to the good seconds before the break when Taylor spilled a Quinn shot, and somehow managed to claw the ball off the goal-line.
Boss Jackett brought on Alan Dunne for Karleigh Osborne in a bid to tighten up the defensive ship at the start of the second period as The Lions reverted to a more familiar flat back four formation.
Right-back Dunne found himself in the referee's book within 20 seconds of the restart for a clumsy rather than malicious challenge on Stephen Quinn, but it did set the tone for a grittier, more determined effort by Millwall.
However, The Lions had a lucky let-off on 52 minutes when the impressive Elmohamady's ferocious shot smashed against the woodwork as Hull went in search of a fifth goal.
Jackett's men managed to get on the scoresheet on 63 minutes when Dunne's delicious dinked delivery hung in the air and Henderson's guided header left Amos grasping at thin air.
Although Millwall tried to further reduce the arrears - no-one more so than the tireless Henry - it ultimately took a fine save from Taylor to prevent Aluko adding a fifth goal for The Tigers in the dying seconds of the game.
Hull City: Amos, Chester, Koren, Simpson, Olofinjana (Evans, 59mins), Dudgeon, Faye, Aluko (Rosenior, 87mins), Elmohamady, Bruce (McShane, 68mins), Quinn. Subs not used: Oxley, Dawson, Mclean, Proschwitz.
Scorers: Koren (14mins), Simpson (32mins), Faye (36mins), Aluko (40mins)
Millwall: M.Taylor, Osborne (Dunne, 46mins), Malone, Abdou, Robinson (Shittu, 78mins), Lowry, Trotter, Wright, Henderson, Keogh, Henry. Subs not used: Forde, Racon, Batt, C.Taylor, N'Guessan.
Bookings: Robinson (41mins), Dunne (46mins)
Scorer: Henderson (63mins)
Ref: J. Adcock
Att: 14,756 (away 252)