The Lions almost fell behind after only two minutes when Anthony Barry sent in a volley from the edge of the area. What would have been the perfect start for the promotion-chasing Glovers was well-saved by Lenny Pidgeley though.
Millwall responded well showing the kind of character that will be required to drag them out of the relegation mire, and a minute later Gary Alexander's downward five-yard header was well-saved by Steve Mildenhall.
Both sides continued to press forward, but showed little guile and gained little reward for their efforts.
Russell Slade's half-time team-talk clearly had the desired effect as Yeovil started the second period brightly.
On 49 minutes Pidgeley turned away Nathan Jones' 25-yard free-kick, but Millwall failed to clear the resulting corner and James Walker popped up in the area to score from eight yards out.
The Lions roared back and, on 71 minutes, Fuseini crossed from the right and Jamie O'Hara arrived at the back post to volley home from ten yards into the bottom right-hand corner.
Yeovil were rattled and they were saved by the woodwork on 78 minutes when Bryan Hodge's 25-yard drive cannoned off the bar.
The Lions scented blood and, on 82 minutes, Fuseini wriggled free of his marker and drove under Mildenhall from 20 yards to give Millwall all three points and make Jackett king of the East End jungle.