Sammy Ameobi's first-half goal had given The Reds a slender lead which they held onto until the final minute of stoppage time when a blistering counter-attack ended with Tyler Walker scoring his first Forest goal since December 2017.
The result was enough to push Forest to within just one point of the automatic promotion places ahead of Tuesday night's meeting with Charlton Athletic at The City Ground.
Sabri Lamouchi made one change from last weekend's defeat to Birmingham City as the returning Samba Sow replaced Ryan Yates in the centre of the Forest midfield. There was also a place on the substitutes' bench for new signing Gaetan Bong following his arrival from Brighton and Hove Albion.
It was an edgy start to the contest as both sides felt each other out and Tiago Silva tested out Leeds goalkeeper Kiko Casilla on two occasions from the egde of the penalty area but the Spaniard was equal to Silva's low efforts.
Marcelo Bielsa's men were looking dangerous coming forward but lacked the cutting edge in attack. Ezgjan Alioski came close as his effort deflected off Joe Lolley on the edge of the Forest box but fortunately for The Reds it drifted wide of Brice Samba's goal.
Forest made the most of that scare as they hit the front two minutes later. Ameobi got his head down and drove into the Leeds penalty area and lashed a shot beyond Casilla to the delight of the ecstatic Reds supporters in the lower tier of the Bridgford Stand.
Arguably, Forest deserved their advantage and they certainly should have doubled the lead ten minutes into the second half. A superb driving run from Lolley made space inside the final third, he laid the ball off to Lewis Grabban and despite shifting it cleverly to the right, he then drilled his shot straight at the legs of Casilla.
The game was tight and nervy as both sides made a number of respective substitutions and it fell to Samba to keep Forest in front with 15 minutes to play. Liam Cooper was left unmarked inside the Forest penalty area and he met a left-wing corner and despite Samba being on the floor at the time, he stretched a hand up into the air to miraculously claw the defender's header off the line.
The City Ground was a stadium packed full of nerves as the game entered its dying embers but those nerves turned to ecstacy in the final minute of stoppage time. Lolley did superbly well to win the ball inside the Leeds half, powered on into the box and squared it to the supporting Walker who tapped home into Casilla's unguarded net.
There was a big-game feel on Trentside and Forest were the team who left with all the glory. Now they must back this result up on Tuesday night as they entertain Charlton Athletic at The City Ground.
Forest: Samba; Cash, Figueiredo, Worrall, Ribeiro; Watson (c), Sow; Lolley, Silva (Yates 80'), Ameobi (Diakhaby 67'); Grabban (Walker 90')
Subs not used: Muric, Bong, Jenkinson, Dawson
Goals: Ameobi 31', Walker 90'
Bookings: Cash 44', Sow 83', Diakhaby 90'
Leeds: Casilla; Dallas, Ayling, Cooper (c), Alioski (Shackleton 70'); White, Costa; Hernandez (Roberts 59'), Klich, Harrison; Bamford (Augustin 71')
Subs not used: Meslier, Berardi, Struijk, Stevens
Bookings: Dallas 35', Alioski 55', White 72'
Referee: Oliver Langford
Attendance: 29,455 (1,993 away)
