Sears’ 83rd-minute winner was the decisive moment, his strike taking a wicked deflection off Forest full-back Michael Mancienne.
The nervous finish was set up, inadvertently, by Town’s Christophe Berra after he deflected Ben Osborn’s cross into his own net after Championship top scorer Daryl Murphy had opened the scoring with his 25th of the season.
The Murphy and Sears combination has seen the duo score a total of seven goals in the last six games, and McCarthy was quick to praise the pairing.
“Murph has had a great season – there was some great link-up between him and Freddie,” the 56-year-old said.
“Freddie has certainly made a big impact since joining and we are delighted with him.
“We may not have deserved to win but the reality is that we won and that’s all that matters at this stage of the season.”
As arguably the most exciting Championship race ever prepares for the final weekend, McCarthy admitted he was surprised that the club’s current points total had not already secured play-off football.
With Ipswich just needing to avoid defeat at Blackburn next Saturday, McCarthy explained: “You would have thought that 78 points would have been enough, but everyone involved in the promotion race has been excellent.
“We have given ourselves a great chance to be involved in the play-offs, but we still have some work to do.”
In a game of few chances, Murphy opened the scoring midway through the first half when he linked up with Sears before drilling the ball under Karl Darlow.
The goal was made all the more special, coming at the same time as Ipswich fans were rising to give a minute’s applause in memory of 21-year-old fan Chris Reynolds.
But they failed to push on with Henri Lansbury going close for the visitors before Forest levelled in the 54th minute.
Chuba Akpom’s fierce drive was parried away by Bartosz Bialkowski, but the pressure was kept up and Osborn’s teasing cross was turned into his own net by Berra.
For most of the final half-hour, Forest looked the most likely to claim three points but Sears’ strike – and Mancienne’s unfortunate deflection – proved the difference.
Forest boss Dougie Freedman said: “It would have been easy for us to turn up and have nothing to play for, but that didn’t happen.
“Over the last five games, the commitment and spirit has been there. We are just lacking a little at both ends of the pitch.
“Mick McCarthy has found a way to get his Ipswich team to win games like that and now we need to find it.
“I have got a good squad here and there was not a lot in that game. I definitely think it will click and the players have shown again that they are going to keep going and give their all for this football club.”