The Terriers lost for the third game running, with a late penalty from Karlan Grant - after Fraizer Campbell was fouled in the area - getting them on the scoresheet, as Forest tightened their grip on a top-six spot.
Huddersfield were relegated from the Premier League last term and have finished the weekend in the Championship's bottom three, following a fourth defeat in six games.
Juninho Bacuna was sent off for a poor challenge on Nuno Da Costa in the final minutes of the contest, meaning he will miss the next three games, in a moment which compounded a frustrating afternoon for the visitors.
Results elsewhere, saw the Terriers drop into the relegation zone on Saturday evening but they are far from adrift and sit just three points behind 18th-placed Charlton Athletic.
Yorkshire rivals Middlesbrough and Hull City also remain in the fray, with Boro only two points in front of the Terriers and the Tigers ahead of Danny Cowley's side on virtue of goal difference.
Lewis Grabban had scored 17 goals for Nottingham prior to the contest and claimed his 18th strike of the season late in the first half.
He connected perfectly with a Joe Worrall cross at the back post to volley the hosts into the lead at the interval.
He added a second within a minute of the second-half restart, taking a through ball from Sammy Ameobi into his stride and curling his effort into the bottom corner.
The home side welcomed back Ben Watson in the only change to their starting line-up from last weekend's draw at Sheffield Wednesday.
The midfielder was fortunate not to concede a penalty midway through the first half when he bundled into Alex Pritchard inside the area.
Danny Cowley opted to make three changes to his side, Pritchard and Andy King replaced Emile Smith Rowe and Juninho Bacuna while Demeaco Duhaney was brought in at right-back for the outgoing Danny Simpson.
Pritchard got forward with intent in the first half, making only his 13th appearance of a season which has been disrupted by injury.
His presence has been missed by the Terriers, who, in the opening 45 minutes, looked much sharper compared to last weekend's disappointing defeat to Wigan Athletic.
Forest could have been ahead inside the first four minutes when former Huddersfield winger Joe Lolley broke into the box and cut a cross back across the box but Sammy Ameobi's shot struck the inside of the post.
Grant, whose goals have been invaluable for the Terriers this campaign, saw his shot in the latter stages of the half hooked off the line by Ameobi.
Smith-Rowe was introduced in the second half and helped Huddersfield create more opportunities but Brice Samba was ever alert in the Forest goal, making one fine save to prevent Grant pulling a goal back with the game at 2-0.
Grabban's brace, with the goals coming either side of the break took the game beyond the Terriers before half-time substitute Ryan Yates prodded home from a corner at the near post to complete the victory for the hosts.
Grant's 16 goals for Huddersfield before the kick off have been worth 12 points to Town but his late penalty was mere consolation as the Terriers now turn their attentions to games against Birmingham City and Preston North End.
Notthingham Forest: Samba; Cash, Figueiredo, Worrall, Ribeiro; Watson (Mighten 90), Silva (Da Costa 73); Lolley (Bostock 90), Johnson (Yates 45), Ameobi (Carvalho 73); Grabban. Unused substitutes:: Smith,Jenkinson, Dawson, Walker.
Huddersfield Town: Lossl; Duhaney (Bacuna 74), Stearman (Stankovic 70), Schindler, Toffolo; Hogg (Chalobah 60), O’Brien; Willock (Campbell 70), Pritchard (Smith-Rowe 60), King; Grant. Unused substitutes: Coleman, Kachunga, Quaner, Daly.
Referee: Referee: David Webb (County Durham).