In a match largely short of quality, both goals came in the early stages of the second half before the two teams reverted to cancelling each other out.
Given Forest's poor away record this season – just four points gained on the road prior to their visit to The Den – it was a better result for them than the Lions, whose habit of drawing too often again left them frustrated.
It was far from the only time Oliver Langford's whistle was heard in the first 20 minutes, during which two players from each side were booked, with the official clearly looking to stamp down his authority.
However, this approach was preventing the match from gaining any type of flow and the ball was rarely able to get out of the midfield area.
The regular free-kicks did at least lead to some shooting opportunities, but Jed Wallace could only fire straight at Forest goalkeeper Brice Samba, while Sammy Ameobi sent a wild effort high and wide.
Ryan Leonard tried his luck from 25 yards shortly before half-time but his strike flew harmlessly over the crossbar.
The early stages of the second half were a total contrast to the first 45 minutes, as Millwall broke the deadlock within two minutes of the restart.
Iceland international Jon Dadi Bodvarsson drove down the left with an excellent run before his cutback was steered into the net by Tom Bradshaw.
However, their lead last just two minutes as a long ball over the top from Mbe Soh led to Mighten's big moment, as the 18-year-old finished well into the bottom corner.
The Lions should have restored their lead in the 52nd minute when Mason Bennett found Wallace in space inside the area but the hosts' top scorer dragged his shot wide.
Things settled down again after that flurry of action and it was Millwall who applied most of the pressure, with Bennett firing way off target after Bradshaw miscontrolled.
Openings were few for the Lions, but Leonard almost snatched victory for them four minutes into stoppage time when his half-volley from outside the box was tipped over by Samba.