The Blues went into their third home match in the space of eight days looking to seal a hat-trick of victories, against a Forest side who have so often struggled on the road since their return to the Premier League. They won just once away from home last season in the League - that tally has already been matched.
After a goalless first-half, Forest took the lead within three minutes of the restart, as Taiwo Awoniyi played the ball through to Anthony Elanga and he passed a finish into the bottom corner.
Mauricio Pochettino turned to his bench heading into the final half an hour, as Cole Palmer was handed a Chelsea debut after his £40m deadline-day move from Manchester City.
He was unable to have any real impact though, with the wall of Forest shirts successfully ensuring Chelsea were unable to convert their possession into much in the way of meaningful chances.
The Blues did create one huge opportunity, as Raheem Sterling skipped to the byline and cut the ball back, but Nicolas Jackson somehow turned the ball over from close range.
Eight minutes of added-time gave the Stamford Bridge faithful hope of a late charge, but Forest held firm for an historic victory in west London.