A Maxime Colin own-goal and Ryan Tunnicliffe's first strike for The Lions secured a much-needed 2-0 televised Sky Bet Championship win over Birmingham City at The Den on Saturday evening.
Colin turned Steve Morison's cross past Tomasz Kuszczak shortly after the half-time break to open the scoring, whilst Tunnicliffe pounced to convert after the stopper parried substitute Tom Elliott's shot.
Lions boss Neil Harris made just one change from last Saturday's 1-0 defeat at Brentford, bringing Morison back into the side at the expense of Shane Ferguson, who dropped to the substitutes' bench.
Millwall's first half-chance came in the fourth minute as Lee Gregory showed outstanding ability to pluck the ball out of the sky and feed Jed Wallace. The winger tried a through-ball back to his team-mate, but it was just overrun and safely into the arms of Kuszczak.
In a highly-charged atmosphere, Gregory had a snapshot on 11 minutes, but with his back to goal, found the stanchion behind the net.
On 17 minutes, George Saville's free-kick found the header of Jake Cooper who turned the ball into the path of Aiden O'Brien, but the Irishman flicked over the crossbar.
The home side were playing some silky passing football and nearly scored a sublime goal on 28 minutes, but Conor McLaughlin's final ball was just cut out by the Blues defence as Gregory was waiting behind.
Birmingham came close to opening the scoring for the first time on 37 minutes, but Che Adams' cross flashed across the face of goal.
Shortly before half-time, Tunnicliffe scooped the ball into the path of Morison, but the striker shot wide. Seconds later at the other end, The Blues could have taken the lead through Isaac Vassell, but his effort thankfully zipped past Jordan Archer's post.
Just two minutes into the second-half, Millwall took the lead. Morison danced his way past two Birmingham defenders and crossed, only for Colin to turn the ball past his own goalkeeper.
It was end-to-end stuff as the already vociferous atmosphere raised up a notch - Adams forced a smart save from Archer on 64 minutes, whilst O'Brien ballooned over a minute later.
With 73 minutes on the clock, Morison attempted to shoot across goal and into the top corner, but Kuszczak was equal to his effort.
Three minutes later, The Lions added a second through Tunnicliffe. Gregory's ball set substitute Tom Elliott away down the left-hand side and after the frontman's shot was parried, the former Manchester United prospect was on hand to fire home for his first goal in a Millwall shirt.
The home side had their tails up and could have added a third through Wallace on 79 minutes, but the winger's looping cross landed on the top of the net.
There were chances at either end to add to the scoring in the final stages, but The Lions held firm to gain three priceless Championship points.
Millwall: Archer, McLaughlin, Meredith, Hutchinson, Gregory (Craig 90+2'), Wallace, Tunnicliffe, Morison (Elliott 74'), O'Brien (Ferguson 69'), Saville, Cooper. Subs not used: Martin, Thompson, Romeo, Twardek.
Scorer: Colin og 47', Tunnicliffe 76'
Booking: McLaughlin, Tunnicliffe
Birmingham City: Kuszczak, Grounds, Roberts, Colin, Kieftenbeld, Vassell, Adams (Boga 77'), Ndoye (Jutkiewicz 70'), Maghoma (Jota 63'), Davis, Morrison. Subs not used: Trueman, Gardner, Dean, Gallagher.
Referee: Simon Hooper
Attendance: 14,797 (2,036)