Substitute Bobby Decordova-Reid added a late third as the Cottagers moved one step closer to automatic promotion back to the Premier League.

It was a fourth defeat in six matches for Millwall, who are eight points off the play-off places.

Both sides capitalised on early mistakes without carving out clear-cut chances, before Fulham settled into the game and started to dictate the tempo.

New signing Neco Williams looked dangerous every time he had the ball on the right-hand side, narrowly missing with a 25-yard effort before cutting back for Mitrovic to open the scoring on 29 minutes.

Millwall goalkeeper Bartosz Bialkowski then got down well to keep out Fabio Carvalho's low left-footed effort.

The home side doubled their lead within five minutes of the restart as Mitrovic lashed home his second goal of the game and 33rd of the season for club and country.

Tim Ream's blocked shot fell to Carvalho, whose effort was well saved by Bialkowski, and the ball dropped nicely for Mitrovic to drill home.

Moments later the striker almost had his fourth hat-trick of the season, when he made room to shoot from the edge of the area, but his powerful right-footed effort went just over.

Mason Bennett looked to be Millwall's most likely route back into the game, twice blazing over with his left foot before dragging a third effort wide with his right foot.

Harry Wilson then broke free down the right with two minutes of normal time left and pulled back for Carvalho.

The teenager's effort fell to Decordova-Reid to seal the win for Fulham.

The game also saw a minute's applause held for Fulham fan Paul Parish, who died after falling ill at the Cottagers' home match against Blackpool on 29 January.

Boss Silva and his players then embraced Mr Parish's family at the Hammersmith End at full-time, in a touching tribute.

Fulham head coach Marco Silva:

"We started a bit slow in our decisions but then we began to command the game.

"[The clean sheet] is really important. We've achieved fantastic scores over the last few games but we've also conceded six goals.

"We know how important it is to keep clean sheets."

On seeing Paul Parish's family at the end: "It was an emotional game for us. When we knew Paul died it was the most sad moment we had this season.

"We knew that, playing well or not, we had to win this football match, they are part of this football club.

"The minimum we could do is have some time with them."

Millwall boss Gary Rowett:

"We performed really well for large parts of the game.

"At 2-0 we had some glaring chances and I thought large parts of it were really promising."

On Mitrovic: "He's a winner, he's ruthless. He knows how to win games and make those moments count.

"That's why he's probably as good as any striker there's ever been in the Championship."