Joe Lolley's ninth goal of the campaign looked set to be the difference between the two sides but Connor Wickham's header in the 93rd minute meant it was a frustrating ending for The Reds on their return to action.
Wednesday made a bright start in front of the vast empty stands at Hillsborough but it was Forest who came close to the opening goal after ten minutes. Tiago Silva whipped a terrific free-kick into the penalty area and Johnson flicked a header inches wide of Joe Wildsmith's goal.
The home side were finding plenty of space down the channels and used that method to carve out a decent chance on 15 minutes. A strong run down the left from Kadeem Harris was followed by a low strike from Massimo Luongo but it narrowly missed the target.
Joe Lolley had looked bright in the opening stages of the contest and Dominic Iorfa was forced to make an excellent block to prevent the Forest man from finding the bottom corner of Wildsmith's net with a low drive from the left-hand side of the penalty area.
It was proving to be a first half of half-chances for both sides as Brice Samba was called into action to smother the ball at the feet of Jordan Rhodes before Liam Palmer made a superb interception to prevent Lolley's through-ball from finding Sammy Ameobi all alone inside the box.
The Reds had two excellent chances to take the lead just before half-time as Lolley's curling free-kick from the edge of the 'D' cleared the crossbar by a matter of inches before the same man provided the cross for Lewis Grabban to head straight at Wildsmith from just outside the six-yard box as the first half ended level.
Forest almost created a superb opening goal shortly after the break. Lolley skipped around his man, raced down the right-hand channel and pulled the ball back for Johnson who was arriving inside the six-yard box but Julian Borner was able to get back well to block it behind for a corner.
It took a moment of incredible defending from Joe Worrall to prevent Wednesday from going in front. A header from Jordan Rhodes beat Samba and hit the post and the ball fell kindly for Kieran Lee to slide into an empty net but Worrall came across with a stunning block to ensure the scores stayed level.
The game was opening up and turning into an entertaining contest and Forest could have been ahead moments later. Johnson did really well to win the ball on the left-hand side but his wicked low cross into the penalty area only just avoided Grabban at the far post.
Both sides had justifiable claims to say they deserved the opening goal but it was Forest who grabbed it on 69 minutes. Matty Cash's pass down the line found Lolley, he skipped past his man into the penalty area and fired the ball beyond Wildsmith into the corner of the net.
Lolley's confidence was high and he stung the palms of Wildsmith with ten minutes to go as the Wednesday stopper was forced to get down low to his left to push behind a powerful strike from the Forest man from 25 yards.
Forest looked set to hold onto their one-goal lead and secure a big three points, with Wednesday huffing and puffing but struggling to create any clear-cut openings. But in injury time, a corner into the Forest box was met by the head of Wickham who planted a header into the top corner, giving Samba no chance.
The Reds have a point to take back to Nottingham as the season gets back underway, when it could have been all three, but there will be plenty of positives to take into the remaining eight games.
Forest: Samba; Cash, Figueiredo, Worrall, Ribeiro; Silva (Bostock 85'), Yates; Lolley, Johnson (Semedo 62'), Ameobi (Da Costa 62'); Grabban (Diakhaby 90')
Subs not used: Smith, Carvalho, Jenkinson, Dawson, Mighten
Goal: Lolley 69'
Bookings: Worrall 68', Cash 72', Silva 78'
Sheffield Wednesday: Wildsmith, Palmer, Lee (Reach 74'), Rhodes (Fletcher 67' (Da Cruz 74')), Harris, Bannan, Borner, Murphy (Odubajo 67'), Wickham, Luongo (Hunt 83'), Iorfa
Subs not used: Dawson, Lees, Fox, Pelupessy
Goal: Wickham 90'
Bookings: Luongo 62', Odubajo 70', Iorfa 90'
Referee: Robert Jones
