Danny Shittu picked the perfect time to score his first goal since November 2013 with a trademark second-half header that put the brakes on Cardiff City's revival under new manager Russell Slade and secured three vital points for The Lions.
Shittu, last on target in a 2-2 draw with Burnley, has a handy habit of scoring important goals for The Lions and his team have not lost on the other two occasions he has been on target against Aston Villa (2-1) and Blackburn (1-0).
The Lions were also indebted to a magnificent double-save from keeper David Forde when the score was at 0-0, denying Craig Noone and then Adam Le Fondre with an incredible piece of agility.
Millwall went into action desperate to end a win-less run stretching back to 30th August when goals from the two Scotts - Malone and McDonald - secured a 2-1 victory over Blackpool.
Since then Holloway's men had lost four and drawn four of their subsequent eight games, including successive draws against Derby (0-0), Wolves (3-3) and most recently Wigan (0-0).
The Lions boss was forced to change the back-line that had dug in for a 0-0 midweek draw at the DW Stadium, with the injured Scott Malone replaced by Matthew and Shittu in for suspended skipper Alan Dunne. Fellow centre-half Byron Webster dropped to the bench to make way for Mark Beevers.
In midfield Shaun Williams was back following a one-match ban whilst Ed Upson returned to the fold with Richard Chaplow and Martyn Woolford named amongst the substitutes.
Cardiff started on the front foot and keeper David Forde was well positioned to gather a long range effort from John Brayford that was deflected into his hands off of Scott McDonald.
Moments later Williams did well to get his body behind Aron Gunarsson's piledriver and block to Cardiff man's effort.
The Lions sent over a couple of inviting deliveries from Briggs on the left and then Upson on the right, but both were comfortably dealt with by the visiting defence.
Beevers went into the ref's book after 11 minutes for a lunging tackle on Anthony Pilkington in a central position around 18 yards. A seven-man wall did its job though and Peter Whittingham's resulting free-kick was cleared.
The visitors continued to look dangerous going forward and were a whisker away from breaking the deadlock on 21 minutes when Adam Le Fondre got behind Beevers, only to see his lofted effort drop onto the roof of the net.
At the other end Lee Gregory, who continues to look stronger with every game, used his strength and control to pick up McDonald's through ball, but just couldn't quite work enough space to get beyond Bruno Ecuele Manga.
Gregory then met Martin's deep free-kick on 26 minutes, but directed his header narrowly wide at the far post.
The Lions, now enjoying their best spell of pressure in the first-half, pressed for the opening goal and Upson's half-volley from the edge of the area flashed a yard.
However it took a world-class double stop from Forde to deny Cardiff taking the lead at the other end eight minutes before the break.
Noone picked up Shittu's headed clearance and hit a rasping drive that Forde did brilliantly to parry at full stretch. The ball feel straight at the feet of Le Fondre who, in steadying himself to take an extra touch, gave Forde just enough time to spread himself and somehow keep out the follow-up.
It took a couple of half-attempts to finally get the ball clear and away from the danger zone, at which point the home crowd stood to applaud a quite sensational piece of goalkeeping from the Republic of Ireland's No. 1.
The second-half sprung into life just nine minutes after the restart when Williams deep corner from the right picked out the formidable figure of Shittu at the far post and he planted a firm header beyond the reach of keeper David Marshall. Spark wild celebrations and a rousing chorus of 'That's what we do' from the Dockers Stand.
Millwall now really had their tails up and could have added further goals when firstly a well-worked routine straight from the training ground ended with Upson's sweetly struck 20-yarder fizzing a foot over the bar and then Gregory raced through only to see his lofted effort drop onto the roof of the net.
Cardiff made a double change just past the hour-mark with Ravel Morrison and Nicky Maynard - so often Millwall's nemesis - replacing Le Fondre and the ineffective Federico Macheda.
But it was The Lions who continued to press with Upson from distance and then Gregory again, this time following an exquisite touch from Fuller in the build-up, both firing narrowly off target.
Holloway had to re-shuffle his defensive pack with 18 minutes remaining when Briggs hobbled off injured and was replaced by Webster, who slotted in at centre-half with Beevers taking care of the left-back berth.
Cardiff enjoyed their best spell of pressure shortly after as they pressed with increasing urgency and numbers in a bid to haul themselves back on level terms. They did, however, have no joy against Shittu, Andy Wilkinson and co as the game headed into the final few minutes.
It was Millwall who had three decent opportunities to put the result beyond doubt as Gregory, Upson and then Woolford all drew saves out of Marshall in the Cardiff goal before the busy Upson lashed the ball agonisingly wide deep into injury-time.
In the end a second goal wasn't needed and The Den was Rockin All Over The World at the final whistle with a special ovation for goalkeeper Forde as he left the field to his second standing ovation of the afternoon.
Millwall: Forde, Wilkinson, Briggs (Webster, 72mins), Beevers, Shittu, Edwards, Upson, McDonald, Gregory, Fuller (Woolford, 78mins), Martin. Subs not used: King, O'Brien, Chaplow, Onyedinma, Abdou.
Bookings: Beevers (11mins), McDonald (90+4mins)
Scorer: Shittu (54mins)
Cardiff City: Marshall, Brayford, Fabio, Manga, Whittingham, Le Fondre (Maynard, 61mins), Noone, Macheda (Morrison, 61mins), Gunnarsson (Ralls, 33mins), Pilkington, S. Morrison. Subs not used: Moore, Connolly, Daehli, Gabbidon.
Ref: S. Duncan
Att: 10,135 (away 786)