A superb first-half strike from Jamie O'Hara fired Millwall to a second successive home win - and out of the bottom four for the first time since August.
Midfielder O'Hara, on loan from Spurs, picked the perfect time to score his first ever senior goal on 33 minutes with a delicious effort into the top corner.
And he was joined on the scoresheet in the eight minutes into the second half by fellow loanee Will Hoskins, who bagged his first goal in a Lions shirt to give the home side a 2-0 advantage.
Bournemouth reduced the arrears with a last-gasp headed effort from Lee Bradbury, but within seconds of the restart referee Andy Hall blew for full-time to send the home fans happy.
With so much at stake, this was always going to be a fiercely fought contest with a lot of effort and commitment on display by both teams.
Millwall had a first sniff of goal on eight minutes when O'Hara whipped in a free-kick from the right only to see the ball flash across the face of goal a foot infront of Hoskins.
Five minutes later a slick six-man move ended with Gary Alexander heading over from another O'Hara cross.
Hoskins, who extended his loan spell from Watford by a further month on Friday, came within inches of opening his goalscoring account for Millwall, but his rasping effort was brilliantly tipped round by Bournemouth keeper Neil Moss.
The Lions did get the ball in the back of the net after 18 minutes when O'Hara's chipped corner found Dave Brammer on the edge of the area, he sent a looping header to Paul Robinson, who had stolen away unmarked at the near post, but Robbo's headed effort was ruled out for offside.
Millwall finally made the all-important breakthrough 12 minutes before the break courtesy of O'Hara's sublime finish from 16 yards after Jay Simspon's cross had been flicked into his path by Hoskins.
A great bit of work by Hoskins and Andy Frampton saw the latter's inviting deep cross headed narrowly wide as the home side began to turn the screw.
Dunne could have added a second goal two minutes into the second half, picking up a fine threaded through pass from Frampton, only to snatch at his shot and drag the ball wide.
But Millwall effectively killed off Bournemouth on 53 minutes, and a lot of the credit belongs to Danny Senda. The Lions right-back surged forward with a lung-bursting run and subsequent cross that Moss could only parry. Although the danger was temporarily averted, Ali Fuseini picked the ball up, took one look and picked out Alexander on the left of the penalty area. The striker unleashed a fierce drive too hot for Moss to handle, and there was Hoskins to calmly steer the ball home from 12 yards.
Bournemouth had a great opportunity to reduce the deficit within seven minutes, only for Bradbury to inexplicably head Jo Kuffour's cross straight into the arms of Rab Douglas from two yards.
At the other end sub Neil Harris did superbly well to prise an opening for O'Hara, but the youngster's effort curled a foot over the bar.
Bournemouth then enjoyed their best period of the match, and it took a marvellous reflex save by Douglas to flick Darren Anderton's goalbound overhead kick clear for a corner.
Although the visitors enjoyed a greater share of the possession at the stage, it was Millwall who could have added a third goal 10 minutes from time when the tireless working Alexander blasted over following another surging run by Dunne.
Ali Fuseini and Dunne both tried their luck from distance as The Lions picked up the pace again, only for Bournemouth to deny the home side a clean sheet when Bradbury headed home Jem Karacan's cross with virtually the last action of the match.

Millwall: Douglas, Senda, Frampton, Brammer (Fuseini, 36mins), Robinson, Shaw, O'Hara (Barron, 77mins), Dunne, Alexander, Hoskins, Simpson (Harris, 70mins). Subs not used: Day, Bakayogo.
Bookings: Brammer (21mins), Robinson (81mins)
Scorers: O'Hara (33mins), Hoskins (53mins)

AFC Bournemouth: Moss, Telfer, Gowling, Cooper, Anderton, Vokes (Kuffour, 54mins), Hollands, Pearce (Lallana, 60mins, (McQuoid 83mins)), Karacan, Bradbury, Wilson. Subs not used: Stewart, Newman.
Scorer: Bradbury (90mins)

Ref: Andy Hall
Att: 7,805 (Away 348)